Pilot study to evaluate the efficacy and safety of pneumatic trabeculoplasty in glaucoma and ocular hypertension.

PURPOSE: Following laser-assisted in situ keratomileusis (LASIK), intraocular pressure (IOP) is measurably lower in a significant number of cases. It has been proposed that the decrease in IOP may be a real event. Prior trials have evaluated pneumatic trabeculoplasty (PNT) in combination with concomitant glaucoma medications. The aim of this study was to determine the efficacy and the safety of PNT alone to lower IOP in patients with primary open angle glaucoma (POAG) or ocular hypertension (OH). METHODS AND RESULTS: A total of 37 subjects with POAG or OH were enrolled in a prospective, open-label, fellow-eye, multicenter trial to determine the IOP lowering effects of PNT. All subjects underwent ophthalmologic examinations and IOP measurements and were washed out from all glaucoma medications prior to the start of the study. The trial was intrapatient controlled for the first 30 days, with one eye receiving PNT at days 0 and 7 and the fellow eye serving as the control. The second eye was treated with PNT at day 30. The patients were followed for 120 days, with the first eye receiving an additional PNT treatment at days 90 and 97. Two analyses-an intent to treat analysis in which the last IOP measurement for patients dropped from the study was carried forward and an analysis including only those patients who completed the trial-were performed. Of the 37 patients enrolled, 27 (73%) completed the study. For the intent to treat analysis the baseline mean IOP was 24.7+/-1.9 mmHg for eye 1 and 23.6+/-2.3 mmHg for eye 2 and the difference was statistically significant (p<0.05). Using this analysis the differences between eye 1 mean IOP at days 1, 7, 14, and 60 and the baseline mean IOP were statistically significant (p<0.05). The differences between eye 2 mean IOP and the baseline mean IOP were statistically significant (p<0.05) at all time points except day 14 and day 30. The greater mean IOP reductions from the baseline mean IOP for eye 1 were at study day 1 (-16,1%), day 14 (-9%), and day 60 (-8.9%). For eye 2 they were at day 60 (-8.7%) and at day 120 (-9.1%). For the analysis that included only those subjects who completed the trial the decrease in eye 1 mean IOP from baseline was statistically significant (p<0.05) at all time points. The decrease in eye 2 mean IOP from baseline was statistically significant at all time points except day 30. Using this analysis the greater mean IOP reductions from the baseline mean IOP for eye 1 were at study day 1 (-19%), day 14 (-15.7%), day 37 (-16.3%), day 60 (-20.0%), day 90 (-18.1%), day 97 (-16.8%), and day 120 (-15.8%). For eye 2 greater mean IOP reductions from baseline mean IOP were seen on day 37 (-13.0%), day 60 (-16.7%), day 90 (-15.5%), day 97 (-14.5%), and day 120 (-7.2%). No statistically significant differences were found in mean IOP reduction between the two eyes treated. A total of 34 patients (92%) showed adverse effects: conjunctival hyperemia in 26 (70.3%) and conjunctival hemorrhage in 14 (37.8%). CONCLUSIONS: This pilot study of PNT showed a potentially good IOP lowering effect on glaucoma and hypertensive patients. Additional studies would help to better define the types of patients who respond to PNT and to identify risk factors that may lead to treatment failure.

Hydrogel intracorneal lenses in aphakic eyes.

BACKGROUND: The theoretical benefits of synthetic keratophakia over conventional corneal lamellar procedures are the elimination of donor concerns and superior refractive predictability. Additionally, synthetic material can be inspected for optical quality and power, and it can be sterilized. Furthermore, visual recovery should be more rapid since epithelium is not removed from the central part of the cornea and the need for keratocyte repopulation is eliminated. OBJECTIVE: To present results on patients who received an intracorneal implant (Kerato-Gel, Allergan Medical Optics, Irvine, Calif) that was made from lidofilcon A, a glucose-permeable hydrogel with an equilibrium water content of 68%. METHODS: The intracorneal implants were implanted in 35 adult patients for correction of aphakia. Inclusion criteria excluded patients with aphakia who were candidates for intraocular lenses. RESULTS: A total of 19 patients were followed up through 2 years postoperatively. For 16 patients with 2-year postoperative refractive data, the average spherical equivalent was -0.63 +/- 2.07 diopters (D). At 2 years, 88% of patients were within +/- 3.00 D of plano and 50% were within +/- 1.00 D. the mean change in Snellen's line for corrected visual acuity was -3.25 lines at 2 years for all patients and -2.0 lines for a subgroup of five patients who were free of vision-limiting preoperative disease. CONCLUSIONS: Results suggest that this intracorneal implant is well tolerated by the cornea and can provide predictable refractive results in patients with high-risk aphakia. Limitations of the procedure are uneven microkeratome resections, loss of best-corrected visual acuity, and irregular astigmatism in some patients. Although these data show good evidence of biocompatibility of the implant material, technical surgical progress is needed to advance this procedure into clinical therapeutic practice.

Refractive surgery.

Myopia (nearsightedness) and hyperopia (farsightedness) are almost equally distributed in the general population but myopia has received the most surgical attention, probably because it produces the greater disability. It also seems more amenable to surgical correction as the widespread successful employment of radial keratotomy bares out. On the other hand, attempts at surgically correcting hyperopia such as hexagonal keratotomy; thermokeratoplasty; hyperopic lamellar keratotomy, and keratophakia have had a less happy experience. Even the more sophisticated technique of laser photoablation is unable to successfully manage hyperopia. It would seem that steepening the cornea is much more difficult than flattening it. Refractive eye surgery is a new subspecialty of ophthalmology only recently come into its own. Considering the tremendous changes in cataract surgery in the past 30 years it is likely that hyperopia will eventually fall to the refractive eye surgeon.

Radial keratotomy: an analysis of the American experience.

A total of 223 patients with bilateral nonprogressive myopia ranging from - to - 11 D underwent partial-thickness radial keratotomy (400 eyes). Topical anesthesia was used for all surgery and all patients had 16 radial incisions from a preset central optical zone, determined by table and/or formula. Neither corneal diameter or scleral rigidity was taken into account in these groups. Substantial reduction of myopia resulted immediately in all cases, with Group 1 showing a 44% regression of the myopia with stabilization occurring at three months. Group 2 showed a 14% regression of effect. In Group 1, 28% attained an unaided visual acuity (postoperatively) of 20/40 or better for most of the day, while 61% of Group 2 attained the same result. Night glare was present in both groups, usually subsiding in three months. Fluctuation was reported in both groups. Side effects were mild. The comparison of the two groups shows that incisions carried almost to Descemet's membrane and deepened in the periphery resulted in much greater reduction of the myopia and a more permanent and stable effect following surgery. New methods of measuring corneal curvature are necessary and a more satisfactory blade needs to be developed for surgery. Corneal thickness measurements have been made more accurate by the development of the ultrasonic pachymeter.

A clinical investigation of the surgical correction of myopia by the method of Fyodorov.

The surgical correction of myopia using the method of Fyodorov known as radial keratotomy consists of 16 partial thickness, radial incisions in the cornea, which result in central flattening and peripheral bulging, reducing the degree of myopia. The purpose of this investigation was to determine: (1) the amount of myopia correctable; (2) the time required for stabilization of corneal curvature changes; (3) the degree to which the variables affect the results; (4) the surgical and postoperative complications; and (5) patient motivation and satisfaction. Preliminary results revealed a significant reduction of the myopia. The keratometry readings and refractive correction required appeared to stabilize by the third month. Fluctuating vision and increased glare were the most frequent complications encountered. The preliminary results of 20 cases followed for six months postradial keratotomy are reported.