Photorefractive keratectomy for low-to-moderate myopia and astigmatism with a small-beam, tracker-directed excimer laser.

OBJECTIVE: To assess the safety and effectiveness of the Autonomous Technologies Corporation LADARVision excimer laser system for photorefractive keratectomy correction of myopia and astigmatism. DESIGN: A multicenter, prospective, noncomparative case series. PARTICIPANTS: The cohort consisted of 467 eyes corrected for spherical myopia and 211 eyes corrected for myopia with astigmatism. INTERVENTION: Treatments were performed at six sites in the United States using a 6-mm ablation zone for spherical myopes and a 5.5-mm zone with a 1.0-mm blend for astigmats. MAIN OUTCOME MEASURES: Visual acuity, subjective refraction, corneal haze, intraocular pressure, complications, adverse reactions, patient satisfaction, and corneal endothelial changes. RESULTS: Twelve-month follow-up was available on 414 spherical eyes and 175 astigmatic eyes. The results for spherical eyes with correction between -1 and -5.99 diopters (D) were: uncorrected visual acuity (UCVA) of 20/40 or better achieved by 98.1%, 20/20 or better by 72%, 1.8% lost 2 lines and 0.3% lost greater than 2 lines of best spectacle-corrected visual acuity (BSCVA); 76.4% were within 0.50 D of the target correction and 94.4% were within 1.00 D. The results for myopia with astigmatism with spherical equivalent correction between -1 and -5.99 D were: UCVA of 20/40 or better in 97.4%, 20/20 or better in 61.7%, 2.5% lost 2 lines and no eyes lost greater than 2 lines BSCVA; 73.9% were within 0.50 D of the target correction and 95% were within 1.00 D. For spherical myopes combined with myopic astigmats corrected for 6 to 10 D, results were: UCVA of 20/40 or better in 93.4%, 20/20 or better in 61.2%, 2.3% lost 2 lines and no eyes lost greater than 2 lines of BSCVA; 67.2% were within 0.50 D of the desired correction and 87.8% were within 1.00 D. Refractive stability was achieved between 3 and 6 months for the spherical and astigmatic groups. No eyes had corneal haze graded as moderate or greater, and there was no significant decrease in endothelial cell density. CONCLUSIONS: Patients treated for 1 to 10 D of spherical equivalent myopia, with or without astigmatism, showed early refractive stability, excellent UCVA, no significant loss of BSCVA, no loss of endothelial cell density, and very low levels of corneal haze to 12 months after surgery.

Efficacy of diclofenac sodium ophthalmic solution versus placebo in reducing inflammation following cataract extraction and posterior chamber lens implantation.

One hundred forty-eight patients were enrolled in a randomized, prospective, placebo-controlled clinical trial evaluating the efficacy of diclofenac sodium (Voltaren Ophthalmic) in reducing ocular inflammation following extracapsular cataract extraction with posterior chamber intraocular lens implantation. Eligible patients were enrolled and randomized (2:1 diclofenac:placebo) if the sum of anterior chamber cells plus flare one day postoperatively (baseline) was at least four. None of the patients received concomitant steroidal anti-inflammatory treatment. The 99 patients receiving diclofenac sodium had significantly greater improvement from baseline in summed flare plus cell score than the 49 placebo patients at two to five days and seven to nine days after baseline. Similarly, diclofenac sodium patients had significantly less post-baseline conjunctival erythema and ciliary flush than placebo patients. Significantly more diclofenac sodium patients than placebo patients showed moderate to marked improvement from baseline in overall assessment of inflammatory response. Forty-nine percent of placebo patients but only 17% of diclofenac patients were considered therapeutic failures (P < .001). By five to seven days, 82% of diclofenac sodium patients and 59% of placebo patients had corrected visual acuities of 20/40 or better (P < .001). There were no clinically important differences in mean intraocular pressure at any visit.

Changing practice patterns in refractive surgery: results of a survey of the American Society of Cataract and Refractive Surgery.

A questionnaire on refractive surgical practice was sent to the entire membership of the American Society of Cataract and Refractive Surgery in 1992. One thousand eight hundred and forty-one (1,841) of the 4,950 members returned the survey for a response rate of 37.2%. The questionnaire was designed to be self-administered and elicited information on types of refractive procedures performed in the survey year and the preceding year, as well as the intent to perform refractive procedures in the future. Surgeons who perform radial keratotomy (RK) increased from 22% in 1991 to 30% in 1992; 45% expected to perform RK in 1993-1994. The following categories of information were requested: characteristics of RK patients, techniques used by the surgeon, characteristics of the surgeon's overall practice, type of RK training, surgical outcome, and prevalence of complications. The results of this survey indicate that the use of RK and astigmatic keratotomy (AK), as well as other refractive procedures, is steadily increasing. Radial keratotomy was mainly performed on patients 20 to 49 years of age who had low to moderate myopia. The majority of surgeons used four to eight radials, centrally directed incisions, and single depth settings. Three quarters of the surveyed RK surgeons used the Casebeer nomogram. The survey results indicated that 42% of surgeons performing photorefractive keratectomy (PRK) did not perform RK or other refractive procedures, suggesting that growth in the practice of PRK following FDA approval may come from both current RK surgeons and novice refractive surgeons.

Initial experience with the HydroSonics instrument to soften cataracts before phacoemulsification.

An ultrasonically driven needle placed into the body of the nucleus, with subsequent injection of balanced salt solution (BSS), can be used to fragment the nucleus into sections or lamellae that can potentially be emulsified with greater ease and less ultrasound energy delivered to the eye. This separation of the nucleus has been designated hydrodelineation. The six surgeons participating in this study subjectively reported that the use of hydrodelineation facilitated phacoemulsification, on average, in 91% of their cases. Review of study data indicated that significantly less ultrasound time and cumulative displayed energy were noted in phacoemulsification of grade 2+ and 3+ cataracts after hydrodelineation than in cases in which hydrodelineation was not performed. The results in cases performed with and without hydrodelineation were statistically equivalent in complications and postoperative patient outcomes.

Improvement in visual acuity in chronic aphakic and pseudophakic cystoid macular edema after treatment with topical 0.5% ketorolac tromethamine.

Ketorolac tromethamine 0.5% ophthalmic solution treatment was compared to placebo treatment in 120 patients with chronic aphakic or pseudophakic cystoid macular edema (six-month or more duration of distance visual acuity of 20/40 or less and angiographic evidence of cystoid changes) during a four- to five-month double-masked, multicenter study in which patients were randomly assigned. A statistically significant improvement in distance visual acuity (two lines or more) was observed in the ketorolac-treated group as compared to the placebo-treated group after 30 days (P = .038), 60 days (P = .017), and 90 days (P = .008) of treatment. This improvement in visual acuity remained statistically significant one month after cessation of treatment (P = .001). Nine ketorolac-treated patients and two placebo-treated patients demonstrated a decrease in visual acuity one month after treatment was discontinued. Seven of the nine ketorolac-treated patients experienced an improvement in visual acuity after retreatment as compared to none of the placebo-treated patients. This study offers evidence for a more optimistic outlook in the medical treatment of chronic aphakic and pseudophakic cystoid macular edema.

Incidence of retinal detachment following posterior chamber intraocular lens surgery.

We examined the three-year incidence of retinal detachment in a consecutive cohort of 4,329 eyes which had cataract surgery with implantation of a posterior chamber intraocular lens between 1979 and 1984. The overall three-year incidence was 1.4%. The three-year incidence for open capsule cases (1.9%) was over twice that for intact capsule cases (0.8%). Axial myopes (axial length greater than or equal to 25 mm) overall were at least three times as likely to develop retinal detachment within three years (3.6%) as eyes with axial lengths less than 25 mm (1.1%). The combination of open capsule and axial myopia increased the three-year retinal detachment risk tenfold over that of the intact capsule in normal length eyes.

Development of the SRK/T intraocular lens implant power calculation formula.

A new implant power calculation formula (SRK/T) was developed using the nonlinear terms of the theoretical formulas as its foundation but empirical regression methodology for optimization. Postoperative anterior chamber depth prediction, retinal thickness axial length correction, and corneal refractive index were systematically and interactively optimized using an iterative process on five data sets consisting of 1,677 posterior chamber lens cases. The new SRK/T formula performed slightly better than the Holladay, SRK II, Binkhorst, and Hoffer formulas, which was the expected result as any formula performs superiorly with the data from which it was derived. Comparative accuracy of this formula upon independent data sets is addressed in a follow-up report. The formula derived provides a primarily theoretical approach under the SRK umbrella of formulas and has the added advantage of being calculable using either SRK A-constants that have been empirically derived over the last nine years or using anterior chamber depth estimates.

Comparison of the SRK/T formula and other theoretical and regression formulas.

We compared the predictive accuracy of the SRK/T formula to the SRK II, Binkhorst II, Hoffer, and Holladay formulas in seven series of cases totaling 1,050 eyes. In the combined group, the SRK/T and Holladay formulas performed only slightly better than the other formulas. In short eyes (less than 22 mm), all formulas performed well, with the SRK/T, SRK II, and Holladay formulas performing marginally better. In moderately long eyes (greater than 24.5 mm, less than or equal to 27 mm), the Hoffer and Binkhorst II formulas had a greater proportion of cases with greater than 2 diopters (D) of error and the SRK/T and Holladay were again marginally better. In the very long eyes (greater than 27 mm and less than or equal to 28.4 mm), there were only 11 cases and all formulas performed well since none had greater than 2 D of prediction error. In an extremely long eye data set (greater than 28.4 mm), the SRK II formula clearly gave the poorest result. Eyes of this length occurred in only 0.1% of cases in our unselected series. Results support the contention that the present second and third generation IOL power formulas give fairly equivalent accuracy. Other factors, such as availability, ease of use, and ability to tailor or individualize, become major considerations.

Inhibition of blood-aqueous humor barrier breakdown with diclofenac. A fluorophotometric study.

Various doses of a new topical nonsteroidal anti-inflammatory agent, diclofenac sodium, were tested against prednisolone sodium phosphate in a randomized double-masked study to determine comparative efficacy and safety regarding the reduction of postsurgical ocular inflammation. Inflammation was assessed by measuring fluorescein leakage into the anterior chamber using fluorophotometry techniques. Increased leakage in each patient's operated-on eye compared with the unoperated-on control eye was attributed to a breakdown in the blood-aqueous barrier caused by the cataract surgery. Elimination or significant reduction of fluorescein leakage within a treatment group constituted increased efficacy in controlling inflammation. A total of 124 cases were analyzed. There were no preoperative differences among groups in fluorescein leakage. At 1 week after surgery, all three diclofenac groups had significantly less fluorescein leakage compared with the prednisolone group. Mean percent increases were 56% to 118% in diclofenac groups vs 324% in the prednisolone group. No differences among diclofenac concentrations were detected. The differences between prednisolone and diclofenac were also present, although of lesser magnitude, at 3 weeks. This demonstration of increased efficacy of the nonsteroidal anti-inflammatory agent vs prednisolone is promising given the known side effects of ocular steroids.

Effect of a pupillary light occluder on cystoid macular edema.

A prospective, randomized study of 291 patients was performed to determine the effect of a pupillary light occluder on the incidence of angiographic cystoid macular edema (CME) in patients having extracapsular surgery with implantation of a posterior chamber lens. Patients were randomized preoperatively into two groups: those having surgery with and without a pupillary light occluder on the cornea. The occluder was placed on the cornea during suture placement, following the extracapsular lens extraction and intraocular lens implantation. Of the 291 patients, 198 had angiograms readable for the presence or absence of CME. The incidence of angiographic CME in patients with the occluder was 15.0%; in those without the occluder it was 12.5%. The difference was not statistically significant. The presence or absence of an occluder on the cornea during suture placement does not affect the incidence of angiographic CME or the visual results of these cases.

The quantitative effect of 0.5% ketorolac tromethamine solution and 0.1% dexamethasone sodium phosphate solution on postsurgical blood-aqueous barrier.

Anterior chamber fluorophotometry was performed after the oral administration of fluorescein sodium in patients undergoing extracapsular cataract extraction and posterior chamber intraocular lens insertion before and after surgery. The administration of 0.5% ketorolac tromethamine solution (ketorolac solution) eye drops before and after surgery decreased the breakdown of the blood-aqueous barrier as compared with 0.1% dexamethasone sodium phosphate solution (dexamethasone solution) eye drops at each period, as measured by fluorophotometry. A single injection below Tenon's capsule of a short-acting corticosteroid had been given to each patient at the end of each surgical procedure. Slit-lamp observations of postoperative ocular inflammation were not different between treatment groups. Both ketorolac and dexamethasone solutions were well tolerated by patients. Ketorolac solution was more effective than dexamethasone solution in facilitating reestablishment of the blood-aqueous barrier after surgery, as measured by fluorophotometry, and was equal to dexamethasone solution as observed by slit-lamp observations. This study suggests that ketorolac ophthalmic solution may be effective and safe as a nonsteroidal anti-inflammatory agent for topical use after cataract surgery and intraocular lens implantation in place of topically administered corticosteroids.

Comparison of the SRK II formula and other second generation formulas.

A simple modification of the SRK formula was developed for use with extreme axial length cases (short and long eyes) to maximize prediction accuracy in these groups. For "average" eyes (over 75% of all cases), SRK needed no modifications to maintain maximum predictive accuracy. The new, modified SRK formula (SRK II) was compared with current second generation formulas and the Binkhorst formula. The SRK II formula, while maintaining the simplicity and ease of the SRK, was comparable to and in some cases superior to the other formulas. Overall, 80.0% of 2,068 posterior chamber intraocular lenses from seven different manufacturers demonstrated less than one diopter of prediction error and only 0.5% had three or more diopters of error. In short eyes (less than 22 mm), 74.0% were corrected to within one diopter and less than 2.0% had three or more diopters of error. In long eyes (greater than or equal to 24.5 mm), 78.0% of cases demonstrated less than one diopter of error and less than 1.0% had three or more diopters of error. Although the SRK II formula is incorporated in most new A-scan units, the modifications are so simple that surgeons can take the standard SRK predictions and mentally calculate the modifications for extreme cases.

Secondary intraocular lens implantation: rigid/semi-rigid versus flexible lenses.

Two series of secondary intraocular lens implantations with anterior chamber lenses are reported. Series 1 consisted of our first 199 consecutive procedures using rigid or semi-rigid lenses, performed between May 1, 1977, and September 30, 1982. Series 2 consisted of our first 101 consecutive procedures using flexible lenses, performed between October 1, 1982, and October 30, 1984. Best-corrected final postoperative visual acuity was either better than or within one Snellen line of best-corrected preoperative vision in 84% of cases with rigid or semi-rigid lenses and in 85% of cases with flexible lenses. Surgical complications were minimal in both series. No instances of uveitis-glaucoma-hyphema syndrome were encountered. Endothelial cell loss was low. Because of the short follow-up in Series 2 and the fact that these groups were operated upon at different times, the two series are not directly comparable. Nonetheless, the results do show that secondary intraocular lens implantation is a viable alternative for aphakic patients, particularly those who are intolerant of aphakic spectacles and contact lenses. Certain provisos involving patient education and motivation as well as lens selection are noted in this report.

A survey of intraocular lens explantations.

A survey of intraocular lens (IOL) explantations performed during the 1984 calendar year requested dates of implantation and explantation, lens manufacturer, and lens style for anterior chamber, posterior chamber, and iris-supported lenses. The survey was distributed to 3,640 members of the American Society of Cataract and Refractive Surgery and was published in the September 15, 1985, issue of Ocular Surgery News. Information on 1,087 IOL explantations performed during 1984 by approximately 530 surgeons was received. Extrapolation of our survey's responses to the universe of ophthalmic surgeons suggests that the number of IOL explantations ranges from 7,000 to 11,000 each year. The actual numbers and percentages of explantations as well as reported complications vary with the relative percentage of any given manufacturer's lenses implanted and with the popularity of lens styles during the preceding years of implantation. For these reasons, the individual performance of various lenses should be read in the context of this report, considering the time of implantation and the practices that were then in vogue. This survey provides a general picture of IOL explantation but, more importantly, it provides a better structure for a report on 1985 explantations, which will follow.

Factors affecting pseudophakic cystoid mascular edema: five randomized trials.

We summarize the findings of five randomized prospective, controlled studies that evaluated the following factors associated with the development of cystoid macular edema (CME) following cataract surgery: ultraviolet (UV) light from the operating microscope; postoperative UV light exposure; primary capsulotomy; retrobulbar hyaluronidase; and prostaglandin synthesis in the eye. The following were the major findings: (1) The presence of a UV-light filter on the operating microscope during cataract surgery made no statistically significant difference in the early postoperative (two to six months) angiographic incidence of CME or the visual outcome. (2) A UV-filtering posterior chamber intraocular lens (IOL) resulted in a statistically significant decrease in the early postoperative incidence of angiographic CME in postcataract-surgery patients but did not affect visual acuity. (3) Patients receiving primary capsulotomy during extracapsular cataract surgery showed a statistically significant higher incidence of early postoperative angiographic CME than did patients with an intact posterior capsule. Again there was no difference in visual acuity. (4) The addition of hyaluronidase to the retrobulbar anesthetic injection made no significant difference in the CME rate or postoperative visual results of patients undergoing extracapsular cataract surgery. (5) Patients undergoing IOL implant surgery who received topical indomethacin before surgery and for nine months postoperatively to inhibit prostaglandin synthesis in the eye showed a statistically significant lower incidence of early postoperative angiographic CME than did placebo-treated patients, but there was no significant difference between the two groups in postoperative visual acuity.

Intraocular pressure and the corneal endothelium after neodymium-YAG laser posterior capsulotomy. Relative effects of aphakia and pseudophakia.

We studied intraocular pressure (IOP) changes and specular microscopic findings in 118 consecutive neodymium-YAG laser posterior capsulotomy procedures; 37 cases were aphakic, and 81 were pseudophakic. There was a significantly greater rise in IOP one hour after Nd-YAG laser treatment in the aphakic group than in the pseudophakic group (8.2 mm Hg vs 3.5 mm Hg, respectively). At one week postoperatively, IOPs in the aphakic group were still significantly elevated over baseline levels (3.6 mm Hg), while those in the pseudophakic group had returned to baseline levels. Differences in treatment between the aphakic and pseudophakic groups in total number of pulses, average energy, and total energy did not explain the differences in IOP. No significant change in endothelial cell densities was seen between pretreatment measurements and those taken one week after Nd-YAG laser treatment.

Effect of an ultraviolet-filtering intraocular lens on cystoid macular edema.

A prospective double-masked study of 301 patients was undertaken to compare the effect of ultraviolet (UV) filtering in implant intraocular lenses (IOL) on the angiographic incidence of cystoid macular edema (CME) in patients undergoing extracapsular cataract extraction. Patients were randomized to receive either a posterior chamber IOL that contained UV-absorbing chromophore or an identical IOL which did not contain such a chromophore. All patients were scheduled for fluorescein angiography between three and six months after surgery; 228 angiograms were obtained that were readable for the presence or absence of angiographic CME. The mean interval following surgery was 4.3 months. The incidence of CME was 18.8% (21 of 112) in patients who received lenses without UV-filtering chromophore and 9.5% (11 of 116) in patients who received IOLs that contained UV-filtering chromophore. These findings show that UV-filtering-IOLs resulted in a statistically significant (P = 0.03) decrease in the incidence of CME. The presence or absence of the UV-filtering chromophore did not, however, significantly affect visual acuity in the early postoperative period.

Near-UV radiation from the operating microscope and pseudophakic cystoid macular edema.

We performed a prospective randomized study of 297 patients to determine the effect of a UV-blocking filter on the operating microscope on the angiographic incidence of cystoid macular edema in patients undergoing extracapsular surgery with implantation of a posterior chamber lens. Patients were randomly allocated preoperatively to two groups undergoing surgery with or without a UV filter in place. Of the 297 patients, 205 had angiograms readable for the presence or absence of cystoid macular edema. The incidence of aphakic cystoid macular edema in patients without the filter was 21% v 17.3% in the group with a filter. This difference was not significant. The presence of a UV-blocking filter on the operating microscope makes no difference in the angiographic incidence of cystoid macular edema or the visual outcome in these cases.

Effect of primary capsulotomy with extracapsular surgery on the incidence of pseudophakic cystoid macular edema.

We performed a prospective randomized study of 288 patients to assess the effect of primary capsulotomy on the angiographic incidence of cystoid macular edema in patients undergoing extracapsular surgery with implantation of an intraocular lens. Patients either had a primary capsulotomy or the posterior capsule remained intact immediately following uneventful posterior chamber intraocular lens implantation. Of the 288 patients, 183 (63%) underwent fluorescein angiography. Angiographically confirmed cystoid macular edema occurred significantly more often in the primary capsulotomy group (20 of 93 patients) than in the intact capsule group (four of 71 patients), for an incidence of 21.5% vs 5.6% (P = .003). The cystoid macular edema appeared milder in the intact capsule group; all the patients with angiographically confirmed cystoid macular edema achieved visual acuities of 20/50 or better. The presence of cystoid macular edema made no difference on visual outcome in the intact capsule group. In contrast, the patients with angiographically confirmed cystoid macular edema in the primary capsulotomy group had significantly worse vision than those who did not have cystoid macular edema (P less than .02).

Prophylaxis and therapy of aphakic cystoid macular edema.

Aphakic cystoid macular edema (ACME) can be a visually significant complication of modern cataract surgery. Prophylaxis of ACME is preferable to therapy of established ACME. Selection of the appropriate cataract operation, control of systemic factors, avoidance of topical catecholamines, control of intraocular inflammation and use of topical or systemic pharmacologic agents may play a role in the prevention of ACME. If it is proven that light toxicity influences the development of ACME, filters in operating microscopes or in intraocular lenses, cataract glasses, or contact lenses may be helpful. Once ACME is present, antiinflammatory therapy has been the main intervention, although its longterm value remains uncertain. Surgical approaches of unproven value have included photocoagulation, vitrectomy, and removal of an intraocular lens.