Preliminary report on the effect of hyperbaric oxygen on cystoid macular edema.

The treatment of established cystoid macular edema has been enigmatic. This is a preliminary study of five patients treated by intermittent hyperbaric oxygen with an intensive regimen of 1.5 hours two times per day for seven days and two hours per day for an additional 14 days. Visual acuity improved within 14 days in all five patients: One patient improved from 20/40 to 20/15, one from 20/50 to 20/25, one from 20/200 to 20/40, one from 20/70 to 20/25, and one diabetic patient improved from 20/70 to 20/25. Vision has tended to regress with time.

Effect of cataract surgery on contrast sensitivity and glare in patients with 20/50 or better Snellen acuity.

The effect of cataract surgery was assessed in 103 patients whose visual acuity, as measured in dim light and with high contrast Snellen letters, was 20/50 or better. The patients desired cataract surgery. They complained of glare symptoms, had given up driving at night, or both. Contrast sensitivity was measured under simulated night conditions with a calibrated Vistech MCT 8000 device. No patient who had a contrast sensitivity of less than 27 at 6 cycles per degree (20/70 "equivalent acuity") had cataract surgery. The mean preoperative contrast sensitivity function showed abnormally low values for all frequencies (cycles/degree) tested. Postoperatively the values returned to normal. Of 99 patients who answered a postoperative questionnaire, 41 (41%) had been driving at night preoperatively and 80 (80%) were driving at night postoperatively. A control group of 24 noncataractous patients (48 eyes) was in the normal range of the test device used. These results support the view that the benefits of cataract surgery are not well predicted by Snellen acuity, even though functional vision may be significantly reduced.

Effect of nasolacrimal occlusion on timolol concentrations in the aqueous humor of the human eye.

We studied the effect of manual nasolacrimal occlusion on the concentration of timolol in the aqueous humor of eyes of patients undergoing cataract extraction. Aqueous humor samples were obtained at various times after timolol maleate instillation from patients with or without 5 min of nasolacrimal occlusion; aliquots were assayed by HPLC. In patients receiving occlusion treatment, average timolol concentrations were statistically greater than those in control patients both between 15 and 90 min after instillation and also at 180 min. Pharmacokinetic analysis indicated that occlusion increased the concentration of timolol in the aqueous humor 1.7 times. In both groups, timolol concentrations were highest approximately 1 h after instillation. The decline in aqueous humor timolol concentrations occurred at similar rates in both groups.

Loss of human photoreceptor sensitivity associated with chronic exposure to ultraviolet radiation.

The crystalline lens of the human eye absorbs most of the incident ultraviolet radiation (UVR), but when the lens is removed, this radiation can reach the photoreceptors. The consequences of UVR exposure on cone receptor sensitivity were determined from psychophysical measurements in patients who had undergone bilateral cataract extraction and implantation of intraocular lenses (IOLs). The IOL implanted in one eye contained chromophores that absorb incident UVR, whereas that implanted in the other eye transmitted UVR. Five years of exposure to ambient UVR was associated with a selective loss in sensitivity of the short-wave cone photoreceptors. These results are consistent with the hypothesis that chronic exposure to UVR may damage the human retina.

Intraocular diclofenac and flurbiprofen concentrations in human aqueous humor following topical application.

Flurbiprofen Na and diclofenac Na, two ocular antiinflammatory agents, were investigated to determine the aqueous humor concentrations in the human eye following topical application. One hundred sixty-five patients undergoing cataract surgery received a single drop of either diclofenac Na or flurbiprofen Na at selected times prior to the surgical procedure. Aqueous humor samples were aspirated at the beginning of surgery and a sensitive high-performance liquid chromatographic assay was used to determine the concentration of the antiinflammatory agent in the ocular fluid. Samples were obtained between 10 min and 24 hrs after a single instillation of the drug onto the cornea. The highest average concentration of diclofenac was 82 ng/ml at 2.4 hrs after instillation; concentrations remained above 20 ng/ml for over 4 hrs. Thereafter, between 3 and 16 ng/ml diclofenac could be assayed through 24 hrs. The highest average concentration of flurbiprofen, 60 ng/ml, was found at 2.0 hrs. The last detectable flurbiprofen concentration was measured at 7.25 hrs after instillation.