1: Invest Ophthalmol Vis Sci. 2010 Aug;51(8):3843-5. 

Author response: donor cell survival in corneal grafts.

Lagali N, Stenevi U, Fagerholm P, Claesson M.

The Department of Ophthalmology, Linkoping University Hospital, Linkoping,
Sweden.

PMID: 20651106  [PubMed - in process]

2: Invest Ophthalmol Vis Sci. 2010 Aug;51(8):3842-3. 

Donor cell survival in corneal grafts.

Wollensak G.

Department of Ophthalmology, Eye Laser Institute, Martin-Luther-University,
Halle, Germany.

PMID: 20651105  [PubMed - in process]

3: Invest Ophthalmol Vis Sci. 2010 Aug;51(8):3841. 

Motion-Encoded MRIs Provide Evidence against Orbital Pulleys.

Jampel RS.

Department of Ophthalmology, Wayne State University, Detroit, Michigan.

PMID: 20651104  [PubMed - in process]

4: Invest Ophthalmol Vis Sci. 2010 Aug;51(8):3841-2. 

Author Response: Motion-Encoded MRIs Provide Evidence against Orbital Pulleys.

Piccirelli M, Luechinger R, Sturm V, Boesiger P, Landau K, Bergamin O.

Institute for Biomedical Engineering, University and ETH Zurich, Zurich,
Switzerland.

PMID: 20651103  [PubMed - in process]

5: Invest Ophthalmol Vis Sci. 2010 Jul 14; [Epub ahead of print] 

Ethnic differences in the prevalence of myopia and ocular biometry in 10-11 year
old children: the Child Heart And Health Study in England (CHASE).

Rudnicka AR, Owen CG, Nightingale CM, Cook D, Whincup P.

Division of Community Health Sciences, St George's, University of London,
London, United Kingdom.

Purpose. Ethnic differences in childhood prevalence of myopia have not been well
characterized in the UK. We examine ethnic differences in refractive status and
ocular biometry in a multi-ethnic sample of British children. Methods Cross
sectional study of school children aged 10-11 years of South Asian, black
African-Caribbean and white European ethnic origin. Vision, open-field
autorefraction (without cycloplegia), and ocular biometry were measured in each
eye. Myopia was defined as spherical equivalent refraction of -0.50D with
unaided vision of 20/30 or worse (in one or both eyes). Ethnic differences in
myopia prevalence were examined using logistic regression; multiple linear
regression for ethnic differences in ocular biometry. All models adjusted for
age, sex, and clustering within school. Results: Data were available for 1179
children. Prevalence of myopia was 25.2%, 10.0%, and 3.4% respectively in South
Asian, African-Caribbean and white European children. Adjusted odds ratios of
myopia compared to white Europeans were 8.9 (95% CI 4.0, 19.4) in South Asians
and 3.2 (95% CI 1.4, 7.2) in African-Caribbean children. Ethnic differences in
myopia prevalence were largely accounted for by ethnic differences in axial
length. South Asian and African-Caribbean children had longer axial lengths
(0.44, 95% CI 0.30, 0.57mm and 0.30, 95% CI 0.16, 0.44mm respectively).
Conclusion: Among British children exposed to the same schooling environment
South Asians have the highest prevalence of myopia, followed by black
African-Caribbeans compared to white Europeans. A quarter of British South Asian
children are myopic, which is strongly related to their increased axial length.

PMID: 20631242  [PubMed - as supplied by publisher]

6: Invest Ophthalmol Vis Sci. 2010 Jul 14; [Epub ahead of print] 

Non invasive assessment of the tear film stability in patients with tear
dysfunction using the Tear Film Stability Analysis System (TSAS).

Gumus K, Crockett CH, Rao K, Yeu E, Weikert MP, Shirayama M, Hada S, Pflugfelder
SC.

Baylor College of Medicine - Cullen Eye Institute, Ophthalmology - Ocular
Surface Center, Houston, United States.

Purpose: To evaluate the tear film stability in patients with tear dysfunction
and an asymptomatic control group using the new non-invasive Tear Stability
Analysis System (TSAS). Methods: In this prospective case control study, 45
patients with dysfunctional tear syndrome (DTS) were stratified into 3 groups
(1, 2, and 3/4), based on clinical severity, with higher scores indicating more
severe symptoms and 25 asymptomatic control subjects were evaluated. TSAS
measurements were performed using the RT-7000 Auto Refractor-Keratometer (Tomey
Corporation, Nagoya, Japan). Images of ring mires projected on to the cornea
every second for 6 seconds were captured and analyzed. Focal changes in
brightness were calculated as numerical Ring Break-Up (RBU) values and the
elapsed time when the cumulative values (RBU Sum) exceeded a threshold was
defined as the Ring Break-Up Time (RBUT). Results: RBUT in DTS groups were all
significantly lower than those of control subjects, with the lowest values found
in DTS 3/4. RBUT was significantly shorter in DTS 3/4 than DTS 1 (P< 0.001). The
change of RBU Sum over a 6-second period in DTS groups combined or among the
individual groups was found to be statistically significant (p<0.001) as was the
difference between the 1 and 6 second values. For distinguishing between
asymptomatic controls and DTS, the sensitivity and specificity of a 5.0 second
RBUT cut-off were 82.0% and 60.0%, respectively. Conclusions: The TSAS may be a
useful non invasive instrument for evaluating tear stability and for classifying
DTS severity.

PMID: 20631241  [PubMed - as supplied by publisher]

7: Invest Ophthalmol Vis Sci. 2010 Jul 14; [Epub ahead of print] 

Incomplete cortical reorganization in macular degeneration.

Liu T, Cheung SH, Schuchard R, Glielmi C, Hu X, He S, Legge GE.

Department of Psychology, University of Minnesota, Minneapolis, United States.

PURPOSE.To addressed three unresolved issues related to cortical activity in
macular degeneration (MD): Is the cortical response to stimuli presented to the
preferred retinal locus (PRL) different from other retinal loci at the same
eccentricity? What is the role of age of onset and etiology of MD? How do
functional responses in visual cortex vary for task and stimulus conditions?
METHODS. Eight MD subjects--4 with age-related onset (AMD), 4 with juvenile
onset (JMD) and two age-matched normal controls, participated in three testing
conditions while scanned with functional magnetic resonance imaging. First,
subjects viewed a small stimulus presented at the PRL vs. a non-PRL location to
investigate the role of the PRL. Second, they viewed a full-field flickering
checkerboard vs. a small stimulus in the original fovea, to investigate the
brain activation with passive viewing. Third, they performed a one-back task
with scene images to investigate the brain activation with active viewing.
RESULTS. A small stimulus at the PRL generated more extensive cortical
activation than at a non-PRL location, but neither yielded activation in the
foveal cortical projection zone. Both passive and active viewing full field
stimuli left a silent zone at the fovea projection zone. The silent zone was
smaller in active viewing compared with passive viewing, especially in JMD
subjects. CONCLUSIONS. The PRL for MD subjects has more extensive cortical
representation than a retinal region with matched eccentricity. There is
evidence for incomplete functional reorganization of early visual cortex in MD.
The functional reorganization is more prominent in JMD. Feedback signals play an
important role in the reorganization.

PMID: 20631240  [PubMed - as supplied by publisher]

8: Invest Ophthalmol Vis Sci. 2010 Jul 14; [Epub ahead of print] 

Lack of oncogenic GNAQ mutations in melanocytic lesions of the conjunctiva as
compared to uveal melanoma.

Dratviman-Storobinsky O, Cohen Y, Frenkel S, Pe'er JJ, Goldenberg-Cohen N.

Felsenstein Medical Research Center, The Krieger Eye Research Laboratory, Petah
Tiqwa, Israel.

Purpose: Somatic mutations in codon 209 of the GNAQ gene are the first
initiating events to be identified in uveal melanoma. The aim of the study was
to search for GNAQ209 mutations in conjunctival melanocytic lesions. Methods:
Forty archival samples of conjunctival melanocytic lesions (conjunctival nevi,
primary acquired melanosis, conjunctival melanoma), 27 samples of uveal
melanoma, and 11 samples of uveal melanoma metastases to the liver (3 of which
matched primary uveal melanoma samples) (total, 78 samples from 75 patients)
were examined for the presence of GNAQ209 mutations using a chip-based
matrix-assisted laser-desorption time-of-flight (MALDI-TOF) mass spectrometer.
Direct sequencing was also performed. Results: The GNAQ209 mutation was
identified in 12 uveal melanoma samples (44.5%) and 4 of the 11 metastases of
uveal melanoma (36.5%). It was not detected in any of the other melanocytic
lesions. Conclusions: The GNAQ209 mutation rate in uveal melanoma in this study
is in line with other reports. The finding of the same genotype in the primary
tumors and their metastases suggests that GNAQ mutation is an early event in
uveal melanoma tumorigenesis. The lack of GNAQ mutations in conjunctival
melanocytic lesions suggests the involvement of a different tumorigenic pathway
from uveal melanoma.

PMID: 20631239  [PubMed - as supplied by publisher]

9: Invest Ophthalmol Vis Sci. 2010 Jul 14; [Epub ahead of print] 

Relationship between Visual Field Sensitivity and Macular Ganglion Cell Complex
Thickness as Measured by Spectral Domain Optical Coherence Tomography (RTVue-100
SD OCT).

Cho JW, Sung KR, Lee S, Yun SC, Kang SY, Choi J, Na JH, Lee Y, Kook M.

Ophthalmology, Asan Medical Center, University of Ulsan, College of Medicine,
Seoul, Korea, Republic of.

Purpose: To evaluate the strength and pattern of relationship between visual
field (VF) mean sensitivity (MS) assessed by standard automated perimetry (SAP)
and macular ganglion cell complex thickness (GCCT) measured using spectral
domain optical coherence tomography (SD-OCT, RTVue-100). Methods: Ninety-seven
glaucoma patients were enrolled. GCCT obtained by Ganglion Cell Complex (GCC)
scanning and two peripapillary retinal nerve fiber layer thickness (pRNFLT)
measurements using the NHM4 (RNFL1) and RNFL 3.45 (RNFL2) modes, were obtained.
MS was recorded on the dB and 1/L scales. Relationship between function (MS) and
structure (GCC, pRNFLT) were sought. Results: The association of MS (dB) with
GCC global (r=0.445) and sectoral (superior, r = 0.528; inferior, r = 0.370)
thicknesses was not significantly different from that of MS to global (RNFL1,
r=0.505; RNFL2, r=0.498) and sectoral (RNFL 1 superior, r=0.559, inferior,
r=0.440; RNFL 2 superior, r=0.535, inferior, r=0.443) pRNFLT, on linear
regression analysis. The relationship pattern was curvilinear on the dB scale
against both GCCT and RNFLTs. Logarithmic regression of MS (using both the dB
and 1/L scales) against both GCCT and RNFLTs was better than linear regression
in describing the pattern of association. Conclusions: GCCT determined by SD-OCT
showed a relationship of similar strength to the corresponding MS as was
demonstrated between MS and pRNFLTs.

PMID: 20631238  [PubMed - as supplied by publisher]

10: Invest Ophthalmol Vis Sci. 2010 Jul 14; [Epub ahead of print] 

Alignment And Cell-Matrix Interactions Of Human Corneal Endothelial Cells On
Nanostructured Collagen Type I Matrices.

Gruschwitz R, Friedrichs J, Valtink M, Franz C, Muller DJ, Funk R, Engelmann K.

Anatomy, TU Dresden, Dresden, Germany.

Purpose: To use nanoscopically defined, two-dimensional matrices assembled of
aligned collagen type I fibrils as a sheet substratum for in vitro cultivation
of human corneal endothelial cells (HCEC). To assess the effect of matrix
architecture on HCEC morphology and to characterize integrin-mediated
HCEC-matrix interaction. Methods: Cell alignment and cell-matrix interactions of
primary HCEC and three different immortalized HCEC populations on native and
UV-cross-linked collagen type I matrices were examined by time-lapse microscopy.
Specific integrin alpha2beta1 binding to the collagen matrix was demonstrated
using a function-blocking alpha2 antibody. Integrin alpha2 subunit expression
levels of the four HCEC populations were analyzed by western blotting. Results:
All HCEC populations aligned along the oriented collagen fibrils. Primary HCEC,
and to a lesser extent also the other tested HCEC populations, exerted high
traction forces, leading to progressive matrix destruction. Cross-linking of the
collagen matrices considerably increased matrix stability. Integrin subunit
alpha2 expression levels of the four cell types correlated with the degree of
cell alignment and exertion of traction forces. In turn, blocking integrin
subunit alpha2 reduced cell alignment and prevented matrix destruction.
Conclusion: HCEC align directionally along parallel arrays of collagen type I
fibrils. The interactions of HCEC with collagen type I are mainly mediated by
integrin alpha2beta1. Integrin subunit alpha2 levels correlate with matrix
contraction and subsequent destruction. Sustained cultivation of HCEC on
ultrathin collagen matrices thus requires matrix cross-linking and moderate
integrin alpha2beta1 expression levels.

PMID: 20631237  [PubMed - as supplied by publisher]

11: Invest Ophthalmol Vis Sci. 2010 Jul 14; [Epub ahead of print] 

Impaired Retinal Circulation in Patients with Type 2 Diabetes Mellitus: Retinal
Laser Doppler Velocimetry Study.

Nagaoka T, Sato E, Takahashi A, Yokota H, Sogawa K, Yoshida A.

Department of Ophthalmology, Asahikawa Medical College, asahikawa, Japan.

Purpose: To evaluate the differences in retinal circulation in patients with
type 2 diabetes with no or early-stage diabetic retinopathy compared to
controls. Methods: Seventy-five nondiabetic eyes and 194 eyes with type 2
diabetes mellitus. Patients were classified into two groups: 139 eyes (139
patients) without diabetic retinopathy (NDR) and 55 eyes (55 patients) with mild
nonproliferative diabetic retinopathy (NPDR). We measured the retinal
circulatory parameters using a Canon Laser Doppler Flowmeter and determined the
factors that affect the retinal hemodynamics in a cross-sectional population of
patients with type 2 diabetes. Results: The group-averaged values of blood
velocity (V) and retinal blood flow (RBF) in the NDR and mild NPDR groups were
significantly (P<0.01) lower than in the non-DM group. The diameter and wall
shear rate were also significantly (P<0.05) lower in the NDR group compared with
nondiabetic controls. Multiple regression analysis showed that the RBF was
independently and negatively correlated with serum low-density lipoprotein and
creatinine. The HbA1c value was significantly (P <0.05) higher in participants
in the lowest RBF quartile than in the highest quartiles. Conclusions: Our
results indicated that the RBF may decrease in patients with type 2 diabetes
without retinopathy and with mild retinopathy.

PMID: 20631236  [PubMed - as supplied by publisher]

12: Invest Ophthalmol Vis Sci. 2010 Jul 14; [Epub ahead of print] 

Insulin growth factor promotes human corneal fibroblast network formation in
vitro.

Berthaut AV, Mirshahi P, Benabbou N, Ducros E, Agra A, Therwath A, Legeais JM,
Mirshahi M.

E18, UMRS872, Paris, France.

Purpose: Corneal fibroblast cell (CFC) reticulation is involved in the
structural development of corneal stroma and in wound healing. In an earlier
paper, we have reported that the expression of VEGFR-1 by CFCs is related to
their reticulogenic properties in vitro and decreased with the age of donors.
Presently, we have focused our interest on the nonreticulogenic corneal
fibroblast population and have investigated whether these cells can be induced
to form cell-network, in vitro, under experimental conditions. Methods: The
network formation was analysed using an array of signalling pathway inhibitors
wortmannin for PI3 kinase, UO126 for MEK-1/2 kinase, Rottlerin for PkC, Farneysl
transferase inhibitor (FTI-277) for Ras and picropodophyllin an IGFR-1
inhibitor. Among several growth factors studied, we came upon IGF which seemed
also to be crucial to cell network formation. The presence of IGF signalling was
demonstrated using gene array analaysis, confirmed by RT-PCR as well as by
immunocytochemistry and cell network formation on reduced matrigel. Pleiotropic
effect of IGF-1 on the cells was analyzed by protein cytokines array. Results:
We identified that the genesis of reticulation occurred via MEK-1/2 and IGFR
pathways since inhibitors of these signaling pathways were able to reduce or
prevent cell network formation. The addition of exogenous IGF-1 was able to
generate cell network structure in corneal fibroblasts obtained from healthy
donors indicating the involvement of IGF-1. Conclusion: IGF signaling and
MEK-1/2 pathway is involved in the cell network formation of corneal fibroblasts
cells from aged donors.

PMID: 20631235  [PubMed - as supplied by publisher]

13: Invest Ophthalmol Vis Sci. 2010 Jul 14; [Epub ahead of print] 

In-Vivo Microstructural Anatomy of Beta-Zone Parapapillary Atrophy in Glaucoma.

Park SC, De Moraes CG, Tello C, Liebmann JM, Ritch R.

Einhorn Clinical Research Center, New York Eye and Ear Infirmary, New York,
United States.

Purpose: To assess the microstructural anatomy of clinical beta-zone
parapapillary atrophy (betaPPA) using Fourier-domain optical coherence
tomography (FD-OCT). Methods: Color photographs and horizontal cross-sectional
FD-OCT images of the optic disc and parapapillary retina were obtained from 24
eyes (24 glaucoma patients or suspects) with betaPPA. The distances between the
temporal disc margin and parapapillary landmarks (clinical betaPPA margin and
the edges of retinal pigment epithelium [RPE], Bruch's membrane [BM], and
photoreceptor inner/outer segment [IS/OS] junction) were measured in 5
equally-spaced horizontal meridians (total 120 meridians). Results: Mean age was
56+/-13 (SD) years. Mean distances from the temporal disc margin to the temporal
betaPPA margin and the edges of RPE, BM, and IS/OS junction in the 5 meridians
were 388+/-173, 371+/-174, 214+/-204, and 502+/-167 microm, respectively. The
RPE edge corresponded to the betaPPA margin in 78/120 (65%) meridians and ended
within the betaPPA in 42/120 (35%) meridians. The BM edge corresponded to the
RPE edge in 13/120 meridians (11%) and was closer to the disc in 107/120
meridians (89%). The disc margin corresponded to the BM edge in 20/120 meridians
(17%) and to the edge of the border tissue of Elschnig in 100/120 meridians
(83%). The IS/OS junction edge was further from the disc than the temporal
betaPPA margin in all 24 eyes. Conclusions: The betaPPA was not completely
denuded of RPE and there was a crescent-shaped area of photoreceptor
degeneration or atrophy peripheral to betaPPA. The termination of the border
tissue of Elschnig constituted the temporal disc margin in most eyes with
betaPPA.

PMID: 20631234  [PubMed - as supplied by publisher]

14: Invest Ophthalmol Vis Sci. 2010 Jul 14; [Epub ahead of print] 

Characterization of Cytoskeletons Enriched Protein Fraction of the Trabecular
Meshwork and Ciliary Muscle Cells.

Inoue T, Pecen P, Maddala R, Skiba NP, Pattabiraman PP, Epstein DL, Rao PV.

Department of Ophthalmology, Duke University School of Medicine, Durham, United
States.

PURPOSE: To understand the molecular basis for the known distinct contractile
characteristics of trabecular meshwork (TM) and ciliary muscle (CM) cells, the
cytoskeletons-enriched protein fractions of the TM and CM cells were isolated
and characterized. METHODS: The Triton-X-100 insoluble fraction enriched for
cytoskeletal proteins was isolated from human and porcine TM tissue and cells,
and from CM cells and characterized by SDS-PAGE, mass spectrometry, and
immunoblotting techniques. RESULTS: The cytoskeletons-enriched protein fraction
derived from both human and porcine TM cells contained plectin 1, filamin A,
non-muscle myosin IIA, clathrin, alpha actinin, vimentin, actin, caldesmon,
myosin IC, and annexin A2 as major proteins, and was noted to exhibit
compositional similarity with the cytoskeletal protein fraction isolated from TM
tissue. Importantly, the cytoskeletal protein composition of the TM cells was
also found to be similar to that noted for CM and vascular endothelial cells.
While the activity of Myosin II, a crucial regulator of cellular contraction,
and a major component of the cytoskeletal protein fraction in TM and CM cells,
was regulated predominantly by Rho kinase in both cell types, myosin light chain
kinase (MLCK) also appeared to control Myosin II activity in CM cells.
CONCLUSIONS: These data reveal that the activity of non-muscle myosin II, a
critical molecule of cellular contraction, was found to be regulated
differentially in TM and CM cells by the Rho kinase and the MLCK pathways
despite their compositional similarity in cytoskeletal protein profile.

PMID: 20631233  [PubMed - as supplied by publisher]

15: Invest Ophthalmol Vis Sci. 2010 Jul 14; [Epub ahead of print] 

An objective approach to dry eye disease severity.

Sullivan BD, Whitmer D, Nichols KK, Tomlinson A, Foulks GN, Geerling G, Pepose
JS, Kosheleff V, Porreco A, Lemp MA.

TearLab, Corp., San Diego, United States.

Purpose: A prospective, multi-site clinical study (10 sites in the E.U. and
U.S.) evaluated the clinical utility of commonly used tests and tear osmolarity
for assessing dry eye disease severity. Methods: 314 consecutive subjects
between the ages of 18-82 years were recruited from the general patient
population, 299 of which qualified with complete datasets. TearLab osmolarity,
Schirmers without anesthesia, tear film breakup time (TBUT), corneal staining,
meibomian dysfunction assessment, and conjunctival staining were performed
bilaterally. A symptom questionnaire (OSDI), was also recorded for each patient.
Distributions of clinical signs and symptoms against a continuous, composite
severity index were evaluated. Results: Osmolarity was found to have the highest
correlation coefficient to disease severity (r2=0.55), followed by conjunctival
staining (r2=0.47), corneal staining (r2=0.43), OSDI (r2=0.41), meibomian
grading (r2=0.37), TBUT (r2=0.30), and Schirmers (r2=0.17). Comparison of
standard threshold-based classification with the composite severity index
revealed significant overlap between the disease severities of prospectively
defined "Normal" and "Dry Eye" groups. Fully 63% of the subjects were found to
be poorly classified by combinations of clinical thresholds. Conclusions: Tear
film osmolarity was found to be the single best marker of disease severity
across normal, mild/moderate and severe categories. Other tests were found to be
informative in more severe forms of disease, thus clinical judgment remains an
important element in clinical assessment of severity. The study also indicates
that the initiation and progression of dry eye is multifactorial, and supports
the rationale for redefining severity of dry eye based on a continuum of
clinical signs.

PMID: 20631232  [PubMed - as supplied by publisher]

16: Invest Ophthalmol Vis Sci. 2010 Jul 7; [Epub ahead of print] 

Genetic inactivation of the adenosine A2A receptor attenuates pathological but
not developmental angiogenesis in mouse retina.

Liu X, Zhou R, Pan Q, Jia XL, Gao WN, Wu J, Lin J, Chen J.

Wenzhou Medical College, Wenzhou, China.

Purpose: The adenosine A2A receptor (A2AR) modulates normal vascularization and
pathological angiogenesis in many tissues, and may contribute to the
pathogenesis of retinopathy of prematurity (ROP) characterized by an abnormal
retinal vascularization in surviving premature infants. Here, we studied the
effects of genetic inactivation of A2AR on normal retinal vascularization and
development of pathological angiogenesis in oxygen-induced retinopathy (OIR), an
animal model of ROP. Methods: After exposure to 75% oxygen for 5 days (P7-P12)
and subsequently to room air for the next 9 days (P13-P21), we evaluated retinal
vascular morphology by ADPase staining in retinal whole-mounts, retinal
neovascularization response by histochemistry in serial retinal sections and
retinal VEGF gene expression by real-time PCR analysis in A2AR knockout (KO)
mice and their wild-type (WT) littermates. Results: At P17, A2AR KO mice
displayed attenuated OIR compared to WT littermates, as evidenced by (a) reduced
vaso-obliteration and area of non-perfusion in the center of the retina, (b)
reduced pathological angiogenesis as evident by decreased non-ganglion cells and
neovascular nuclei and (c) inhibited hypoxia-induced retinal VEGF gene
expression. Notably, attenuation of pathological angiogenesis by the A2AR
inactivation was selective for OIR since it did not affect the normal retinal
vascularization during postnatal development. Conclusion: These findings provide
the first evidence that the A2AR is critical for the development of OIR, and
suggest a novel therapeutic approach of A2AR inactivation for ROP by selectively
targeting the pathological but not developmental angiogenesis in the retina.

PMID: 20610844  [PubMed - as supplied by publisher]

17: Invest Ophthalmol Vis Sci. 2010 Jul 7; [Epub ahead of print] 

EFFECT OF AGE ON THE THIOLTRANSFERASE (GLUTAREDOXIN) AND THIOREDOXIN SYSTEMS IN
THE HUMAN LENS.

Xing KY, Lou MF.

School of Veterinary and Biomedical Sciences, University of Nebraska-Lincoln,
Lincoln, United States.

Purpose: To investigate the effect of age on the key oxidation repair enzymes of
the thioltransferase (TTase) and thioredoxin (TRx) systems in the human lens.
Methods: Twenty three normal human lenses of 19-77 yrs were grouped into 2nd,
3rd, 5th, 6th and 7th decades, and analyzed for TTase, TRx, glutathione
reductase (GR), thioredoxin reductase (TR), and glyceraldehyde-3-phosphate
dehydrogenase (G3PD) activities, as well as the glutathione (GSH) pool.
Additionally, nineteen contralateral lenses of the above donor eyes were each
divided into cortex and nucleus for enzyme distribution studies. Results: All
the above enzymes showed similar activity in the cortex and nucleus, regardless
of age, but were inactivated to various extents in the older lenses. In the
TTase system, both TTase and GR showed activity loss over the 5 decades, with
70% remaining in the 7th decade, while the GSH pool was depleted extensively,
with only 35% left in the older lenses. In the TRx system, TRx activity was not
affected as much as TR for which only 70% of the activity was found in the 7th
decade compared with the 2-3 decades. Overall G3PD was more sensitive to age, as
only 50% activity remained after the 6th decade. Conclusions: With increasing
age there is a gradual activity loss in both the TTase and TRx systems, and a
lowered GSH pool. These alterations compounded with the age-related loss in G3PD
activity may lead to redox and energy imbalance, likely contributing to a higher
risk to cataract formation in the aging population.

PMID: 20610843  [PubMed - as supplied by publisher]

18: Invest Ophthalmol Vis Sci. 2010 Jul 7; [Epub ahead of print] 

Pattern-related visual stress, chromaticity and accommodation.

Allen PM, Hussain A, Usherwood C, Wilkins AJ.

Postgraduate Medical Institute, Vision and Eye Research Unit, Cambridge, United
Kingdom.

Purpose: To investigate the impact of coloured overlays on the accommodative
response of individuals with and without pattern-related visual stress (PRVS), a
condition in which individuals manifest symptoms of perceptual distortion and
discomfort when viewing a 3 cycles per degree square-wave grating. Methods:
Under double-masked conditions, 11 individuals who reported PRVS selected an
overlay with a colour individually chosen to reduce perceptual distortion of
text and maximise comfort (PRVS group). Two groups of controls, individually
matched for age, gender and refractive error were recruited. Control Group 1
similarly chose an overlay as maximising comfort. Control Group 2 used the same
overlays as the paired PRVS participant. The overlay improved reading speed by
10% (p<0.001), but only in the PRVS group. Using a remote eccentric
photorefractor, accommodative lag was recorded while participants viewed a cross
on a background. The background was uniform or contained a grating and was
either grey in colour or had a chromaticity identical to that of the chosen
overlay. There were therefore four backgrounds in all. Results: Overall, the
accommodative lag was 0.44D greater in the participants with PRVS. When the
background had the chosen chromaticity, the accommodative lag was reduced by an
average of 0.16D (p=0.03) in the PRVS group, but not in the symptom-free groups:
in Control Group 2 the coloured background slightly increased the accommodative
lag. Conclusion: Accommodative lag was greater in individuals susceptible to
pattern-related visual stress and was reduced by coloured backgrounds.

PMID: 20610842  [PubMed - as supplied by publisher]

19: Invest Ophthalmol Vis Sci. 2010 Jul 7; [Epub ahead of print] 

Peripheral ocular aberrations in mild and moderate keratoconus.

Atchison DA, Mathur A, Read SA, Walker MI, Newman AR, Tanos PP, McLennan RT,
Tran AH.

School of Optometry, Queensland University of Technology, Kelvin Grove,
Australia.

Purpose: To investigate the influence of keratoconus on peripheral ocular
aberrations. Methods: Aberrations of 7 mild and 5 moderate keratoconics were
determined over a 42 degrees horizontal x 32 degrees vertical visual field with
a modified COAS-HD aberrometer. Control data were obtained from an emmetropic
group. Results: Most aberrations in keratoconics showed field dependence
predominately along the vertical meridian. Mean spherical equivalent M, oblique
astigmatism J45 and regular astigmatism J180 refraction components and total
root mean square aberrations (excluding defocus) had high magnitudes in the
inferior visual field. The rates of change of aberrations were higher in
moderate than in mild keratoconics. Coma was the dominant peripheral
higher-order aberration in both emmetropes and keratoconics; for the latter it
had high magnitudes in the centre and periphery of the visual field. Conclusion:
Greater rates of change of aberrations across the visual field occurred for the
keratoconic groups than for the emmetropic control group. Moderate keratoconics
had more rapid changes in, and higher magnitudes of, aberrations across the
visual field than mild keratoconics. The dominant higher-order aberration for
the keratoconics across the visual field was vertical coma.

PMID: 20610841  [PubMed - as supplied by publisher]

20: Invest Ophthalmol Vis Sci. 2010 Jul 7; [Epub ahead of print] 

Myosin Heavy Chain Expression in Mouse Extraocular Muscle: More Complex Than
Expected.

Zhou Y, Liu D, Kaminski HJ.

Neurology and Psychiatry, Saint Louis University, Saint Louis, United States.

PURPOSE: To characterize the expression patterns of myosin heavy chain (MyHC)
isoforms in mouse extraocular muscles (EOM) during postnatal development.
METHODS: MyHC isoform expression in mouse EOM from P0 to 3 months was evaluated
by qPCR and immunohistochemistry. The longitudinal and cross-sectional
distribution of each MyHC isoform and co-expression of certain isoforms in
single muscle fibers was determined by single, double and triple
immunohistochemistry. RESULTS: MyHC isoform expression in postnatal EOM follows
developmental rules observed in other skeletal muscles, however important
exceptions were found. First, developmental isoforms are retained in the orbital
layer of the adult EOM. Second, expression of emb-MyHC, neo-MyHC and 2A-MyHC is
restricted to the orbital layer and that of 2B-MyHC to the global layer. Third,
although slow-MyHC and 2B-MyHC do not exhibit obvious longitudinal variations,
emb-MyHC, neo-MyHC and 2A-MyHC are more abundant distally and excluded from
innervational zone, while eom-MyHC complements their expression and is more
abundant at the mid-belly region in both orbital and global layers. Fourth,
co-expression of MyHC isoforms in single global layer fibers is rare, but it is
common among orbital layer fibers. CONCLUSION: MyHC isoforms have complex
expression patterns exhibiting not only longitudinal and cross-sectional
variation for each isoform, but also of co-expression in single fibers. The
highly heterogeneous MyHC expression reflects the complex contractile profiles
of EOM, which in turn are a function of the requirements of eye movements, which
range from extremely fast saccades to sustained position, each with a need for
precise coordination of each eye.

PMID: 20610840  [PubMed - as supplied by publisher]

21: Invest Ophthalmol Vis Sci. 2010 Jul 7; [Epub ahead of print] 

MEIBOMIAN LIPID FILMS AND THE IMPACT OF TEMPERATURE.

Butovich IA, Arciniega JC, Wojtowicz JC.

Department of Ophthalmology, UTSouthwestern Medical Center, Dallas, United
States.

Purpose. There is evidence that in cold conditions the temperature of human
eyelids and of the ocular surface may drop well below normal physiological
levels. This may have a detrimental impact on the stability and functionality of
the human tear film and the tear film lipid layer. The goal of this project was
to quantitatively examine the possible impact of temperature on the latter.
Methods. Meibum samples were collected using the soft-squeezing technique and
studied in a Langmuir trough. The obtained surface pressure/area isotherms were
analyzed to determine the biophysical parameters of thin meibomian lipid films
(MLF) - the lift-off area, collapse pressure, two-dimensional elasticity,
hysteresis, and their dependence on temperature. Results. MLF were found to be
highly susceptible to changes in temperature. At temperatures below the
physiological level, MLF became stiff and shrunk considerably. This left a large
portion of the air/water interface uncovered with lipid molecules. This effect
was shown to be reversible: upon reheating, the lipids melted and re-spread to
restore the original film. There was a fundamental difference observed between
three-dimensional melting of dry meibum in bulk and their two-dimensional
melting in MLF at the air/water interface: bulk meibum melted in a narrower
temperature range and showed a much higher cooperativity of melting.
Conclusions. Temperature critically influences MLF. Low temperature leads to
stiffening of MLF which lose their ability to form continuous layers at the
air/water interface. These effects were shown to have a cooperative nature
manifesting themselves in relatively narrow concentration and temperature
ranges.

PMID: 20610839  [PubMed - as supplied by publisher]

22: Invest Ophthalmol Vis Sci. 2010 Jul 7; [Epub ahead of print] 

Prevalence and Risk Factors for Cataract in Diabetes. Sankara Nethralaya
Diabetic Retinopathy Epidemiology And Molecular Genetics Study Report No 17.

Raman R, Pal SS, Adams JS, Rani PK, Vaitheeswaran K, Sharma T.

Vitreoretinal services, Sankara Nethralaya, Chennai, India.

Purpose: To report the prevalence of cataract and its subtypes in patients with
type II diabetes mellitus and the risk factors associated with these cataracts.
Methods: One thousand two hundred and eighty three eligible subjects with type
II diabetes mellitus, enrolled from a cross-sectional study, underwent
examination at the base hospital. The grading of lens opacity, as per the Lens
Opacity Classification System (LOCS) III system, was performed by a trained
ophthalmologist. Results: The age and gender adjusted prevalence of cataract in
the study was 65.7%, 95%CI (65.6-65.8) respectively. Mixed cataracts were more
common than the monotype cataracts (41.6% Vs 19.4%). The prevalence of cataract
was higher in women, subjects with known diabetes, and those with longer
duration of diabetes (51.4%, 50.3% and 64.5%, respectively). The risk factors,
for any type of cataract, were increasing age [OR 1.14 , 95%CI (1.11-1.16)],
macroalbuminuria [OR 4.61, 95% CI (1.56-13.59)] and increasing glycosylated
hemoglobin [OR 1.92, 95%CI (1.22-3.00)]; higher hemoglobin [OR 0.38, 95%CI
(0.22-0.64)] was the protective factor. The risk factors for nuclear cataract
included increasing age (OR 1.15) and high serum triglycerides (OR 6.83). For
cortical cataract, increasing age (OR 1.14) and poor glycemic control (OR 2.43)
were the risk factors; increasing hemoglobin (OR 0.41) was the protective
factor. For posterior subcapsular cataract, the risk factors included:
increasing age (OR 1.11), women (OR 9.12), employment (OR 9.80) and duration of
diabetes (OR 21.37). Conclusions: Nearly two-third of the diabetic population
showed evidence of cataract; mixed cataracts were more common than the monotypes
ones.

PMID: 20610838  [PubMed - as supplied by publisher]

23: Invest Ophthalmol Vis Sci. 2010 Jul 7; [Epub ahead of print] 

Quantifying sensory eye dominance in the normal visual system: a new technique
and insights into variation across traditional tests.

Li J, Lam CS, Yu M, Hess RF, Chan LY, Maehara G, Woo GC, Thompson B.

State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen
University, Guangzhou , China.

PURPOSE. Although eye dominance assessment is used to assist clinical decision
making, current understanding is limited by inconsistencies across the range of
available tests. We have developed a new psychophysical test of sensory eye
dominance that objectively measures the relative contribution of each eye to a
fused suprathreshold binocular percept. METHODS. We measured motor and sensory
dominance in a group of 44 binocularly normal individuals (mean age,
29.5+/-9.10) using 6 standard tests and our new test. The new test required
observers to perform a motion coherence task under dichoptic viewing conditions,
whereby a population of moving luminance-defined signal (coherently moving) and
noise (randomly moving) dots were presented separately to each eye. Observers
judged the motion direction of signal dots. Motion coherence thresholds were
measured by varying the ratio of signal to noise dots using a staircase
procedure. RESULTS. The new dichoptic motion coherence threshold test revealed a
clear bimodal distribution of sensory eye dominance strength, whereby the
majority of participants (61%) showed weak dominance but a significant minority
(39%) showed strong dominance. Subsequent analysis revealed that the strong
dominance group showed greater consistency across the range of traditional eye
dominance tests we used. CONCLUSIONS. Our new quantitative dichoptic motion
coherence threshold technique suggests that there are two separate sensory eye
dominance strength distributions among observers with normal binocular vision;
weak and strong eye dominance. This may provide a basis for clinical decision
making by indicating whether eye dominance is likely to be an important
consideration for a particular patient.

PMID: 20610837  [PubMed - as supplied by publisher]

24: Invest Ophthalmol Vis Sci. 2010 Jul 7; [Epub ahead of print] 

Selective Activation of the Prostaglandin E2 Circuit is a Key Component of
Chronic Injury-Induced Pathological Angiogenesis.

Liclican EL, Nguyen V, Sullivan AB, Gronert K.

Vision Science Program, School of Optometry, University of California, Berkeley,
Berkeley, United States.

Purpose: Cyclooxygenase (COX)-derived prostaglandin E(2) (PGE(2)) is a prevalent
and established mediator of inflammation and pain in numerous tissues and
diseases. Distribution and expression of the four PGE(2) receptors (EP1-4) can
dictate whether PGE(2) exerts an anti/pro-inflammatory and/or pro-angiogenic
effect. The role and mechanism of endogenous PGE(2) in the cornea, and
regulation of EP expression during a dynamic and complex inflammatory/reparative
response remain to be clearly defined. Methods: Chronic or acute self-resolving
inflammation was induced in mice by corneal suture or epithelial abrasion,
respectively. Re-epithelialization was monitored by fluorescein staining and
neovascularization quantified by CD31/PECAM-1 immunofluorescence. PGE(2)
formation was analyzed by lipidomics and PMN infiltration quantified by
myeloperoxidase activity. Expression of EPs and inflammatory/angiogenic
mediators was assessed by real-time PCR and immunohistochemistry. Mice eyes were
treated with PGE(2) (100 ng topically, t.i.d.) for up to seven days. Results:
COX-2, EP-2 and EP-4 expression was upregulated with chronic inflammation which
correlated with increased corneal PGE(2) formation and marked
neovascularization. In contrast, acute abrasion injury did not alter PGE(2) or
EP levels. PGE(2) treatment amplified PMN infiltration and the angiogenic
response to chronic inflammation, but did not affect wound healing or PMN
infiltration after epithelial abrasion. Exacerbated inflammatory
neovascularization with PGE(2) treatment was independent of the VEGF circuit but
was associated with a significant induction of the eotaxin-CCR3 axis.
Conclusion: Our findings place the corneal PGE(2) circuit as an endogenous
mediator of inflammatory neovascularization rather than general inflammation,
and demonstrate that chronic inflammation selectively regulates this circuit at
the level of biosynthetic enzyme and receptor expression.

PMID: 20610836  [PubMed - as supplied by publisher]

25: Invest Ophthalmol Vis Sci. 2010 Jun 30; [Epub ahead of print] 

Role of c-Cbl Dependent Regulation of Phospholipase C gamma 1 Activation in
Experimental Choroidal Neovascularization.

Husain D, Meyer R, Mehta M, Pfeifer WM, Chou E, Navruzbekov G, Ahmed E, Rahimi
N.

Ophthalmology, Boston University School of medicine, Boston, United States.

Purpose: Activation of phospholipase C gamma1 (PLCgamma1) by vascular
endothelial growth factor receptor-2 (VEGFR-2) is required for proliferation and
tube formation of endothelial cells in vitro. Previous work from our laboratory
has demonstrated that Casitas B-lineage lymphoma (c-Cbl) promotes ubiquitination
of PLCgamma1 and suppression of its tyrosine phosphorylation. This study is
designed to evaluate the importance of PLCgamma1 and c-Cbl in experimental
choroidal neovascularization (CNV). Methods: We studied the role of PLCgamma1 in
three models of angiogenesis: the endothelial cell culture system, the
chorioallantoic membrane assay (CAM), and the laser-induced CNV model.
Endothelial cells were analyzed for the role of PLCgamma1 to undergo tube
formation. CAMs were incubated with pharmacological agents that either inhibit
or stimulate PLCgamma1. Data were recorded using a digital analysis system. CNV
was induced in the wild-type and c-Cbl knockout mice, and the progression of CNV
was evaluated by fluorescein angiography. Results: Activation of PLCgamma1 is
required for tube formation of endothelial cells. PLCgamma1 stimulation
increases the growth of blood vessels and conversely, PLCgamma1 inhibition
decreases the growth of blood vessels in the CAM model. CNV lesions in the c-Cbl
knockout mice were significantly greater in number, more confluent, and
increased in size with time compared to control wild-type mice. Conclusions: The
data show that PLCgamma1 plays an important role in angiogenesis. Loss of c-Cbl
results in enhanced CNV in the eye. Our study also show that c-Cbl plays an
important role in ocular angiogenesis suggesting that modulation of c-Cbl
activity or inhibition of PLCgamma1 may be is a compelling target for
anti-angiogenesis therapy.

PMID: 20592236  [PubMed - as supplied by publisher]

26: Invest Ophthalmol Vis Sci. 2010 Jun 30; [Epub ahead of print] 

Human optical axial length changes in response to defocus.

Read SA, Collins M, Sander B.

Optometry, Queensland University of Technology, Brisbane, Australia.

Purpose: To investigate the short term influence of imposed monocular defocus
upon human optical axial length (the distance from anterior cornea to retinal
pigment epithelium) and ocular biometrics. Methods: Twenty-eight young adult
subjects (14 myopes and 14 emmetropes) had eye biometrics measured before and
then 30 and 60 minutes after exposure to monocular (right eye) defocus. Four
different monocular defocus conditions were tested, each on a separate day:
control (no defocus), myopic (+3 D defocus), hyperopic (-3 D defocus) and
diffuse (0.2 density Bangerter filter) defocus. The fellow eye was optimally
corrected (no defocus). Results: Imposed defocus caused small but significant
changes in optical axial length (p<0.0001). A significant increase in optical
axial length (mean change +8 +/- 14 microm, p=0.03) occurred following hyperopic
defocus, and a significant reduction in optical axial length (mean change -13
+/- 14 microm, p=0.0001) was found following myopic defocus. A small increase in
optical axial length was observed following diffuse defocus (mean change +6 +/-
13 microm, p=0.053). Choroidal thickness also exhibited some significant changes
with certain defocus conditions. No significant difference was found between
myopes and emmetropes in the changes in optical axial length or choroidal
thickness with defocus. Conclusions: Significant changes in optical axial length
occur in human subjects following 60 minutes of monocular defocus. The
bi-directional optical axial length changes observed in response to defocus
implies the human visual system is capable of detecting the presence and sign of
defocus and altering optical axial length to move the retina towards the image
plane.

PMID: 20592235  [PubMed - as supplied by publisher]

27: Invest Ophthalmol Vis Sci. 2010 Jun 30; [Epub ahead of print] 

A Central Dip in the Macular Pigment Spatial Profile is Associated with Age and
Smoking.

Kirby ML, Beatty S, Loane E, Akkali M, Connolly EE, Stack J, Nolan JM.

Macular Pigment Research Group, Chemical & Life Sciences, Waterford Institute of
Technology, Waterford, Ireland.

Purpose: To investigate the relationship between specific macular pigment (MP)
spatial profiles and risk factors for age-related macular degeneration (AMD).
Methods: The MP spatial profile of 484 healthy subjects was measured using
customised heterochromatic flicker photometry (cHFP) and categorised into one of
two profile types (typical exponential or atypical 'central dip'). Data on risk
factors for AMD were obtained using a general health and lifestyle
questionnaire. Dietary and serum concentrations of lutein (L) and zeaxanthin (Z)
were also assessed. Results: The presence of the 'central dip' MP spatial
profile was significantly more common in older subjects (mean +/- SD age of
subjects with a 'central dip' MP spatial profile was 46.9 +/- 12 years, while
the mean age of subjects with a 'typical' MP spatial profile was 41.8 +/- 12
years, p = 0.004) and in current cigarette smokers (p = 0.031). Also, there was
a significant age-related decline in central MPOD (0.25 degrees retinal
eccentricity), but in males only (r = -0.146, p = 0.049). Conclusions: A
'central dip' in the MP spatial profile, seen in older subjects, and in
cigarette smokers, might potentially represent an undesirable feature of macular
pigmentation. Further research is needed in this area.

PMID: 20592234  [PubMed - as supplied by publisher]

28: Invest Ophthalmol Vis Sci. 2010 Jun 30; [Epub ahead of print] 

Structure-Function Relationships in Normal and Glaucomatous Eyes Determined by
Time Domain and Spectral Domain Optical Coherence Tomography.

Lee JR, Jeoung JW, Choi J, Choi JY, Park KH, Kim YD.

HanGil Eye Hospital, Incheon, Korea, Republic of.

Purpose: To compare relationships between retinal mean sensitivity (MS) and
retinal nerve fiber layer (RNFL) thickness as measured by time domain (TD) and
spectral domain (SD) optical coherence tomography (OCT). Methods: Recruited
subjects were divided into normal, glaucoma suspect, and glaucoma groups. RNFL
thickness was measured using TD OCT (Stratus OCT) and SD OCT (Cirrus HD-OCT),
and MS was assessed using the Humphrey visual field analyzer and expressed in
units of dB and 1/L. The relationship between SUPERIOR MS and INFERIOR RNFL
thickness (clock-hour segments 5, 6, 7, 8) and that between INFERIOR MS and
SUPERIOR RNFL thickness (clock-hour segments 10, 11, 12, 1, 2, 3) were
correlated using linear and logarithmic regression analyses. Pearson's
correlation coefficients, R values, for both OCTs were compared using
Hotelling's t-test. Results: Ninety-five eyes of 76 subjects were prospectively
included. Twenty-five eyes were classified as normal, 25 as glaucoma suspect,
and 45 with glaucoma. In normal and glaucoma suspect eyes, there were no
significant relationships between MS and RNFL thickness. In glaucomatous eyes, R
values for the association between MS and RNFL thickness were 0.31 - 0.57 with
TD OCT, and 0.47 - 0.66 with SD OCT, and the correlation of SUPERIOR RNFL
thickness with INFERIOR MS was significantly better using SD OCT compared with
TD OCT in both linear and logarithmic regression models. Conclusion: Our study
showed that SD OCT offered improved structure-function correlation, compared
with TD OCT, when applied to INFERIOR MS and SUPERIOR RNFL defects, in
mild-to-moderate glaucoma.

PMID: 20592233  [PubMed - as supplied by publisher]

29: Invest Ophthalmol Vis Sci. 2010 Jun 30; [Epub ahead of print] 

Altered calcium signalling in an experimental model of glaucoma.

Niittykoski M, Kalesnykas G, Larsson K, Kaarniranta K, Akerman K, Uusitalo H.

Department of Ophthalmology, University of Kuopio, Kuopio, Finland.

Purpose. To investigate calcium signalling in a rat experimental model of
glaucoma. Methods. A method for labeling the ganglion cell layer (GCL) neurons
with the calcium indicator Fura-2 in flat-mounted retinas of adult rats was
established. Pharmacologically evoked responses in laser-induced glaucomatous
and control retinas were imaged 2 weeks after the initial laser treatment. The
optic nerves of the same eyes were evaluated for neurodegenerative changes.
Results. After laser treatment, intraocular pressures (IOPs) were elevated 1.5 -
4.9-fold (24.70 +/- 15.57 mmHg) compared to control eyes (8.71 +/- 1.53 mmHg)
and the area of neurodegenerative axons in optic nerve sections of laser-treated
eyes was increased by 1.2 - 13.3-fold. The basal intracellular Ca2+ level, as
revealed by the Fura-2 ratio, was elevated in GCL cells of laser-treated eyes as
compared to controls. This might suggest a mild degree of damage at the level of
the soma in the GCL cells from eyes with elevated IOP. While glaucomatous GCL
neurons remained functional as assessed pharmacologically, analysis of imaging
data revealed that responses evoked by a brief application of ATP were slightly
reduced rather than increased in the cells of laser-treated eyes as compared to
controls. No significant relationships were found between IOP/optic nerve damage
and functional characteristics (basal intracellular Ca2+ level or response to
carbachol/elevated K+/ATP) within cells of laser-treated eyes. Conclusions. Ca2+
imaging is a useful tool to map altered physiological characteristics of
individual GCL neurons in the glaucomatous eye.

PMID: 20592232  [PubMed - as supplied by publisher]

30: Invest Ophthalmol Vis Sci. 2010 Jun 30; [Epub ahead of print] 

Effect of Induced Myopia on Scleral Myofibroblasts and in vivo Ocular
Biomechanical Compliance in the Guinea Pig.

Backhouse S, Phillips JR.

Department of Optometry and Vision Science, The University of Auckland,
Auckland, New Zealand.

Purpose. To examine the effect of induced myopia on scleral myofibroblast
populations and in vivo ocular biomechanical compliance. Methods. One week old
guinea pigs were monocularly deprived (MD) of form vision for two weeks. Ocular
biomechanical compliance was measured in both eyes of anaesthetised animals by
increasing the intraocular pressure (IOP) to 50 mmHg for one hour, while A-scan
ultrasound measures were made every 10 minutes to investigate the change in
axial length. The total cell population and myofibroblast sub-population of the
posterior 100 degrees of the sclera was determined using immunohistochemical
techniques. Results. The vitreous chamber depth (VCD) of MD and contralateral
control eyes showed significant elastic expansion on increasing the IOP,
compared to un-manipulated normal eyes. The creep response of the VCD to
increased IOP was initially greater in normal eyes until eye length was similar
to the MD and control eyes. An unexpectedly high proportion of the scleral cell
population were myofibroblasts (63.7 +/- 1.7% average +/- SEM; n = 30,). MD
significantly decreased total cell numbers in the region between the optic nerve
and 10 degrees nasal (equivalent to myopic crescent location in humans) compared
with control or normal eyes, but no significant effect on myofibroblast or total
cell numbers was found elsewhere. Conclusions. A high proportion of scleral
cells have contractile potential. This proportion is unaffected by MD. However,
there is a significant difference in the in vivo elastic response of the sclera
between MD and normal eyes, suggesting factors other than cell number have an
effect on axial length.

PMID: 20592231  [PubMed - as supplied by publisher]