Vitreoretinal alterations following laser in situ keratomileusis: clinical and experimental studies.

BACKGROUND: The presence of vitreoretinal changes following laser in situ keratomileusis in myopia is evaluated. METHODS: Clinically, 50 patients (100 eyes) with marked anisometropic myopia, 50 low-myopic eyes (<4.00 D) and 50 high-myopic eyes (>7.00 D) were prospectively evaluated pre- and postoperatively for the presence of newly recognized entoptic phenomena (vitreous floaters, light flashes, or both), and for vitreoretinal changes using indirect depressed fundus examination, a +90 D preset lens, Goldman three-mirror contact lens, and kinetic ultrasound (KU) before and after bilateral LASIK. Patients with previous partial or total posterior vitreous cortex detachment (PVD) were excluded. Experimentally, groups of adult pigs underwent KU, retinal fluorescein angiography (FA), and electroretinography (ERG) before and after applying the microkeratome suction ring for 30 s. RESULTS: Clinically, 8% (4 eyes) had positive perception of postoperative vitreous floaters in the low myopia group, and 32% (16 eyes) in the high myopia group. Postoperative light flashes were noted only in the high myopia group, in 12% of cases. Partial or total posterior vitreous cortex detachment was detected by biomicroscopy in 2% (1 eye) of the low and in 10% (5 eyes) of the high myopia group and by KU in 4% (2 eyes) of the low and in 24% (12 eyes) of the high myopia group. Experimentally, 2 pig eyes out of 12 developed partial PVD by KU, immediately after microkeratome suction ring application. All pig eyes showed significantly diminished ERG amplitudes during and immediately after suction ring application. No FA changes or delays in retinal circulation time were noted during or immediately after removal of the suction ring. CONCLUSIONS: Vitreoretinal alterations after LASIK were demonstrated clinically mainly by KU in high myopes. Experimentally, PVD were also demonstrated. Diminished ERG recordings with normal retinal circulation following suction ring application may suggest some transient choroidal circulation abnormalities.

A forced choice comfort study of olopatadine hydrochloride 0.1% versus ketotifen fumarate 0.05%.

PURPOSE: To compare the ocular comfort of two ophthalmic anti-allergic agents: olopatadine hydrochloride 0.1% and ketotifen fumarate 0.05%. SUBJECTS AND METHODS: In a double-masked, multi-centered, randomized trial, 80 subjects were asked to make a 'forced choice' based on ocular comfort between one drop of olopatadine hydrochloride 0.1% instilled in one eye and one drop of ketotifen fumarate 0.05% instilled in the contralateral eye. At one site, the incidence of adverse reactions was also reported. RESULTS: All subjects (100%) selected olopatadine as the more comfortable formulation. One site (n = 35) reported a 49% incidence of moderate burning and a 49% incidence of mild burning after ketotifen instillation. One subject (2% of population) at this site experienced no ocular discomfort with ketotifen. There were no reports of discomfort associated with olopatadine instillation. CONCLUSION: Olopatadine is a more comfortable ophthalmic preparation than ketotifen.