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Research Digest

New & Noteworthy Journal Articles

Compiled by Andrew E. Mathis, PhD, Medical Editor

■ Optic disc topography in Graves disease. The relationship between Graves disease and glaucoma is uncertain. To determine whether patients with Graves disease have thinner retinal nerve fiber layers (RNFLs) than controls, ophthalmologists in Turkey undertook a case-control study of 65 patients and 54 controls. They reported their findings in the December 2012 issue of the Journal of Glaucoma.

All subjects were submitted to retinal tomography and had their IOP measured. Mean IOP in the Graves patients was 14.6 ± 2.9 mm Hg vs. 13.4 ± 2.1 mm Hg in the controls, a difference the authors described as statistically significant.

In addition, mean RNFL thickness was 0.25 ±0.05 mm in the Graves patients vs. 0.31 ±0.08 mm in the controls. Mean RNFL cross-sectional area was also greater in the controls. The authors concluded that Graves disease could cause significant changes in the RNFL, and they suggested regular optic nerve head monitoring could aid in early diagnosis of glaucoma in such patients.

■ Cup-to-disk ratio in RVO. Compartment syndrome, in which the optic disc has either a small cup or no cup, has been reported to occur with retinal vein occlusion, although it is more common in ischemic optic neuropathy. The November 2012 issue of Retina featured a report by doctors at the University of Iowa, who studied 1,222 eyes with RVO as a means for investigating the relationship of compartment syndrome and RVO.

The study authors prospectively examined the cup-to-disc ratio in these eyes, as well as visual acuity, fundus photography, fluorescein angiography and other tests. Compared to normal eyes, eyes with central RVO more commonly had cup-to-disc ratios ≥0.5, as well as moderate hemorrhages. Eyes with other vein occlusions were not significantly different from control eyes. There was no association of cup-to-disc ratio with macular edema or visual acuity.

The authors rejected the thesis of a correlation of compartment syndrome with RVO, and they recommended not applying radial optic neurotomy in such eyes.

■ Keratoconus and corneal edema. In the December 2012 issue of the American Journal of Ophthalmology, a study team reported their findings on persistent corneal edema after collagen cross-linking (CXL) for keratoconus, positing persistent corneal edema as a new complication.

The authors performed a retrospective case series of patients with corneal edema following CXL. At a mean follow-up of 14 ± 4 months, 10 of 350 patients had postoperative corneal edema. In all 10 patients, edema began on day 1 postoperatively and continued to increase over the following three weeks. Half of these patients ultimately had their edema resolve or improve.

In addition, the next most common adverse events were iris atrophy, pigment dispersion, persistent epithelial defects, deep vascularization and infectious keratitis. Two patients whose edema had not improved at three months underwent penetrating keratoplasty. The study authors concluded that in some severe cases of edema, PK will be necessary.

■ Graft diameter in DSAEK. What influence does graft diameter have on endothelial cell loss in patients with Fuchs dystrophy undergoing DSAEK? To answer this question, cataract surgeons undertook a retrospective, interventional case series of 695 eyes, reporting their results in the January 2013 issue of Cornea.

In the 695 cases examined, the graft sizes ranged between 7.5 and 9.5 mm. Focusing on grafts of 8.5 or 9 mm, the mean baseline donor endothelial cell density was 3,039 cells/mm² and 3,026 cells/mm², respectively. Mean endothelial cell density decreased over time in both graft size groups, and there was no significant difference between the groups. The groups also had similar rejection and graft dislocation rates.

The authors concluded that while a larger graft size would seem to indicate healthier endothelial cells, their study did not support that theory. They recommended prospective studies to examine the issue.

■ High myopia and OCT in glaucoma. Spectral-domain OCT parameters can be used to detect glaucoma, but does comorbid high myopia affect that ability? According to an article in the December 2012 issue of Graefe’s Archive of Clinical and Experimental Ophthalmology, measurement of circumpapillary RNFL thickness was made more difficult.

The investigators studied 179 eyes, both glaucomatous and non-glaucomatous, divided into groups — with and without high myopia — and used OCT to measure circumpapillary RNFL thickness and macular ganglion cell complex.

While the measurements for ganglion cell complex were similar between the groups, circumpapillary RNFL thickness differed significantly, with the measurements inferior in the high myopia group. The authors concluded that OCT measurements should be applied complementarily.

■ Quality of vision in cataract surgery. In the November 2012 issue of the British Journal of Ophthalmology, collaborating ophthalmologists from Italy, the United Kingdom and Australia reported their results in administering the Quality of Vision questionnaire to 212 patients with and without ocular comorbidities before and after cataract surgery.

The authors found significant improvements in subjective ratings of vision quality in all study groups. Blurred vision as an outcome was correlated with subcapsular cataracts. They concluded that ocular comorbidities did not subjectively affect quality of vision after cataract surgery. OM