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Objective: Leber's hereditary optic neuropathy is a maternally inherited form of visual loss that is associated with several mitochondrial DNA mutations. These mitochondrial DNA mutations are not the sole determinants of visual loss, as epigenetic factors may play a pathogenetic role. To clarify the role of these factors, we studied two visually discordant twins and determined their zygosity and mitochondrial genotype., Design: Case series., Setting: Referral center., Patients: Identical twin brothers from a family with the 11778 mitochondrial DNA mutation., Main Outcome Measures: Visual acuity, results of testing for visual fields (measured with static and dynamic perimetry) and color vision, and results of funduscopic examination; alcohol and tobacco use, head trauma, co-existent medical illness, and occupational exposure; and results of mitochondrial DNA analysis and determination of zygosity., Results: The monozygous twin brothers have remained discordant for the development of optic neuropathy for 6 1/2 years despite harboring the identical homoplasmic 4216, 13708, and 11778 mitochondrial DNA mutations., Conclusions: The patients are visually discordant despite being genetically identical at the nuclear and mitochondrial levels. Epigenetic factors are important determinants of visual loss in Leber's hereditary optic neuropathy in these brothers. Among those factors studied in these patients, a substantial difference was noted in regard to occupational exposure to toxic substances. Epigenetic factors that may influence the clinical expression of the mitochondrial DNA mutations associated with Leber's hereditary optic neuropathy should be systematically studied. Risk-factor intervention strategies should be formulated and implemented.

Objective: To formulate a systematic approach to the surgical management of subluxed posterior-chamber intraocular lenses (IOLs)., Design: We reviewed the records of 31 consecutive patients who underwent anterior-segment surgery for IOL subluxation. Presumed anatomic causes of IOL subluxation were identified in 28 cases (90%). Three surgical procedures were used to correct the implant subluxation: modified McCannel sutures (19 eyes), IOL exchange (eight eyes), or IOL rotation (four eyes)., Results: Twenty-nine (94%) of the 31 patients obtained a postoperative visual acuity of 20/40 or better. Surgical complications included persistent vitreous in the anterior chamber (three cases), progressive capsular opacification (two cases), and anterior chamber and vitreous hemorrhage (one case)., Conclusions: Our results show that, by implementing a planned surgical approach, subluxed posterior-chamber IOLs can be safely and effectively managed.

We performed a prospective study that evaluated whether pretreatment with topical flurbiprofen alters the intraocular pressure (IOP) lowering effects of either topical 1% apraclonidine hydrochloride or 0.5% timolol maleate. Eighteen normal volunteers participated in this six-armed, randomized, double-masked, crossover study. All subjects received the first study medication, either bilateral 0.3% flurbiprofen or placebo (its vehicle), every 30 minutes for four applications. They next received the second study medication: either 0.5% timolol maleate (Timoptic), 1% apraclonidine hydrochloride, or placebo in both eyes. We measured IOP before the instillation of the first study medication and the second study medication (baseline), and then at 1, 3, and 6 hours later. All subjects underwent all six treatment arms. Flurbiprofen alone had no effect on IOP. Maximum IOP lowering occurred between 3 and 6 hours after timolol and apraclonidine administration. There was no difference in IOP lowering between timolol- and apraclonidine-treated eyes. Pretreatment with flurbiprofen did not affect the IOP lowering that was obtained with timolol or apraclonidine administration.