Factors Associated with Occurrence of Radiation-induced Optic Neuropathy at "Safe" Radiation Dosage.

BACKGROUND: Radiation-induced optic neuropathy (RION) is a rare, and often visually devastating, complication of radiation therapy (RT) near the anterior visual pathways. METHODS: A retrospective case series of patients who developed RION at a tertiary medical center, followed by a case-control study comparing RION cases with matched controls who received RT. RESULTS: Thirteen patients (18 eyes) with RION were identified. Radiation modalities included external beam photon radiation, whole brain radiation, stereotactic radiosurgery, proton beam, and unknown. Most patients received doses below published "safe" thresholds (<55 Gy; <8-10 Gy for stereotactic radiosurgery). There was no statistically significant difference in prevalence of vasculopathic factors between cases and controls; on subgroup analysis in three patients who received surprisingly low radiation doses, smoking (p=0.05) and hypertension (p=0.02) appeared more prevalent. CONCLUSION: RION can occur at doses below published "safe" thresholds and with different RT modalities. Smoking and hypertension might be risk factors for RION.

Comparison of distance and near visual acuity in patients with vision loss due to cataract.

The purpose of this study was to assess whether there is a disparity in distance and near best-corrected visual acuity (BCVA) in cataract eyes. 102 patients with cataract (N = 121 eyes) were seen in clinic between January and November 2013 at the Wilmer Eye Institute Comprehensive Eye Service. An age-related macular degeneration (ARMD) group (N = 27 eyes) was also identified for comparison. Distance and near BCVA were measured as part of the standard ophthalmic evaluation. Snellen measurements were converted to their LogMAR equivalents for statistical analysis. Near was better than distance BCVA with mean difference of 1.38 lines (P < 0.001) in the cataract eyes. This disparity was not seen in the ARMD eyes. Near-distance BCVA disparity is a statistically significant finding seen with cataracts. This may have further implications in patients with both cataract and ARMD as the presence of disparity may suggest a cataract etiology playing a greater role in vision loss. This comparison may be useful for surgical prognostication and as a quick triage tool in conjunction with, or in place of, a potential acuity meter and dilated near-pinhole test.

Sarcoidosis Presenting with Cicatrizing Conjunctivitis.

PURPOSE: To report two patients with sarcoidosis initially presenting with cicatrizing conjunctivitis. CASE REPORTS: Both patients with chronic conjunctivitis were referred for further management. The first patient had conjunctival granulomas, subepithelial fibrosis, and forniceal foreshortening. The second patient had extensive upper and lower conjunctival scarring with forniceal foreshortening and symblepharon formation of both eyes. Conjunctival biopsy specimens revealed noncaseating granulomas. Immunofluorescein studies were negative for immunoreactant deposition in the basement membrane. Because of further diagnostic evaluations, sarcoidosis was determined to be the final cause of the cicatrizing conjunctivitis. CONCLUSIONS: Sarcoidosis should be included in the differential diagnosis of cicatrizing conjunctivitis. Recognition of the characteristic noncaseating granulomas in the conjunctival biopsy and initiation of the appropriate evaluations are essential in establishing the diagnosis and determining the extent of systemic involvement.

Photographic simulation of off-axis blurring due to chromatic aberration in spectacle lenses.

Spectacle lens materials of high refractive index (nd) tend to have high chromatic dispersion (low Abbé number [V]), which may contribute to visual blurring with oblique viewing. A patient who noted off-axis blurring with new high-refractive-index spectacle lenses prompted us to do a photographic simulation of the off-axis aberrations in 3 readily available spectacle lens materials, CR-39 (nd = 1.50), polyurethane (nd = 1.60), and polycarbonate (nd = 1.59). Both chromatic and monochromatic aberrations were found to cause off-axis image degradation. Chromatic aberration was more prominent in the higher-index materials (especially polycarbonate), whereas the lower-index CR-39 had more astigmatism of oblique incidence. It is important to consider off-axis aberrations when a patient complains of otherwise unexplained blurred vision with a new pair of spectacle lenses, especially given the increasing promotion of high-refractive-index materials with high chromatic dispersion.