Intraocular lens power calculations using corneal topography after photorefractive keratectomy.

PURPOSE: To report two patients (two eyes) with previous photorefractive keratectomy, who subsequently underwent cataract extraction years later. DESIGN: Case reports. METHODS: Corneal topography was used to determine corneal power used in intraocular lens power calculations. RESULTS: In two eyes of two patients, intraocular lens calculations after photorefractive keratectomy were inadequate, which resulted in a hyperopic postoperative refractive error requiring implantation of a piggyback intraocular lens. CONCLUSION: Corneal topography to determine corneal power in patients with previous photorefractive keratectomy may result in unpredictable intraocular lens power calculations. The clinical history method is the standard to determine corneal power and should be considered in intraocular lens calculations before cataract surgery. We recommend supplying refractive patients with preoperative data for use in future formulas for intraocular lens selection.

Phase II results of an intraocular steroid delivery system for cataract surgery.

OBJECTIVE: To evaluate the safety and efficacy of an intraocular biodegradable polymer dexamethasone drug delivery system (DEX DDS) in treating postoperative inflammation after cataract surgery. STUDY DESIGN: Multicenter, randomized, double-masked, parallel group study comparing two dose levels of the DEX DDS to concurrent placebo and no treatment control subjects. PARTICIPANTS: Ninety patients scheduled to undergo extracapsular cataract extraction with phacoemulsification and intraocular lens implantation participated in the study. INTERVENTION: One or two DEX DDSs, each containing 60 microg of dexamethasone, were placed in the posterior chamber after cataract surgery. Patients receiving the placebo received a DDS composed of the same matrix with no active drug. In vivo rabbit studies have determined that the DEX DDS releases dexamethasone into the anterior chamber (AC) for approximately 7 to 10 days. MAIN OUTCOME MEASURES: The AC cells and the AC flare were assessed over a 60-day postoperative period using slit-lamp examination by masked observers. The number and percent of patients in each treatment group requiring additional postoperative topical anti-inflammatory medication were compared. RESULTS: Ninety patients were randomized into 4 treatment groups (30 to the 2 DEX DDS group, 30 to the 1 DEX DDS group, 15 to the placebo DDS group, and 15 to the no treatment group). The control patients required the addition of topical steroids as rescue medication more frequently and sooner than patients receiving DEX DDS (80% vs. 7% at week 2) (P < 0.001). Patients receiving DEX DDS showed a significant reduction in postoperative inflammation as assessed by the combined AC cell and flare scores when compared to the control group from day 3 (P = 0.002) through week 3. The DEX DDS was well tolerated. No clinically significant difference in any safety evaluations, including intraocular pressure, was seen between the DEX DDS-treated and control groups. CONCLUSION: The DEX DDS was safe and effective in suppressing postoperative inflammation after uncomplicated cataract surgery. Additional topical anti-inflammatory drops were not needed for most patients.

Long-term clinical results of AMO PhacoFlex model SI-18 intraocular lens implantation.

The AMO PhacoFlex Model SI-18 was the first commercially available three-piece silicone intraocular lens (IOL) for use in small incision cataract surgery. Allergan Medical Optics' silicone IOLs have been implanted in more than 750,000 patients worldwide over the past eight years. This report of the FDA clinical investigation of the AMO PhacoFlex model SI-18 IOL summarizes one year follow-up data from the initial premarket approval clinical trial on 500 core patients implanted with the SI-18 lens. One-year follow-up data from 5,860 patients in the modified core group and three-year follow-up data on the 500 patient core/modified core group are also presented. At three years postoperatively, 91.3% of best case core/modified core patients achieved 20/40 or better corrected visual acuity. Overall incidence of persistent complications at three years was 3.2%.

Phacoemulsification with intraocular lens implantation after excimer photorefractive keratectomy: a case report.

We report the first case, to our knowledge, of phacoemulsification with lens implantation in a patient with previous photorefractive keratectomy for myopia. Intraocular lens calculations were performed using manual and automated keratometry. The surgical and postoperative course were uneventful with a good visual outcome. Standard intraocular lens calculation and surgical technique appear to be successful for cataract extraction after photorefractive keratectomy.

Arcuate keratotomy for the correction of spherical hyperopia in human cadaver eyes.

BACKGROUND: A new experimental surgical technique to correct spherical hyperopia by steepening of the central corneal curvature was performed on human cadaver eyes. METHODS: Ten eyes were used in the study. All were pretreated with glycerin to ensure a uniform corneal thickness between .55 and .65 mm on ultrasonic pachometry. A constant intraocular pressure of approximately 30 to 40 mm Hg was maintained in each eye by the injection of saline into the vitreous cavity. This was verified by pneumotonometry. A vertical blade diamond knife was set at 100% of the thinnest of four paracentral readings. Each eye underwent preoperative computed topography. One set of five eyes had 12 incisions made following a 5.75-millimeter diameter Mendez hexagonal marker that included unconnected T incisions at each junction (ie, "Hex T" pattern). The other set of five eyes had four arcuate incisions made following a 6-millimeter diameter zone marker; each incision was 60 degrees in arc. Immediately after surgery, computed topography was repeated. RESULTS: The hexagonal keratotomy set of eyes had an average steepening of the cornea of 0.80 D with a range of -1.05 to + 4.38 D. The arcuate keratotomy set had an average steepening of +2.12 D with a range of +1.27 to +3.27 D. CONCLUSIONS: This study suggests arcuate keratotomy may be a more effective procedure in the correction of spherical hyperopia when compared with hexagonal keratotomy. The amount of corneal steepening achieved in a cadaver eye model may not be the same as when performed in vivo.

Topographical analysis of the centration of excimer laser photorefractive keratectomy.

A major advantage of myopic photorefractive keratectomy (PRK) is the precision with which the excimer laser ablates corneal tissue. But like other refractive surgery procedures, PRK must solve the problem of accurately centering the treatment zone. We present our technique for PRK centration with postoperative corneal topographic data on 110 patients from Phase IIB and III of the clinical trials. The distance between the center of the post-PRK flat zone and the corneal vertex was determined by topography in millimeters and meridian degrees. On average, treatment zones were decentered down and right 0.52 mm at 196.74 degrees; 92.73% were centered within 1.00 mm, while 57.27% were within 0.50 mm. The centration data were correlated to postoperative visual acuity as well as treatment zone diameter. Mean uncorrected visual acuity was 20/20 for decentrations up to 1.00 mm but fell to 20/30 for deviations greater than 1.00 mm. Best corrected acuity was also preserved below 1.00 mm but compromised above this level. No difference in decentration was found between 4.5 mm and 5.0 mm ablation zones. Our findings indicate that PRK centration is accurate within 1.0 mm in over 92% of cases and that visual acuity is relatively preserved despite deviations from perfect centration. Further technical improvements will enhance the accuracy of PRK.

Centration of excimer laser photorefractive keratectomy relative to the pupil.

The centration of excimer laser photorefractive keratectomy (PRK) is critical to the procedure's success. We evaluated PRK centration in 49 patients using the EyeSys topography system. Ablation zone centration was measured from the corneal vertex and from the pupillary center using the pupil-finding software. Centration was measured more accurately from the pupillary center (0.40 mm) than from the corneal vertex (0.44 mm). Right eyes were decentered less than left eyes. There was an unpredictable correlation between amount of decentration and postoperative visual acuities. The ability to measure centration of keratorefractive procedures precisely from the pupil is an important advance in topography technology.

The nationwide study of epikeratophakia for aphakia in older children.

A nationwide study of epikeratophakia for aphakia in older children was conducted from March 1984 to March 1986. Sixty-three patients, 8 to 18 years of age, underwent this procedure in 65 eyes. Twenty-eight patients had congenital cataracts and 35 had traumatic cataracts. Fifty-one of the 65 eyes were aphakic at the time of surgery (secondary procedures). All surgeries were successful; no tissue lenses were lost or removed. Postoperatively, 73% of the patients were within 3 diopters (D) of emmetropia. The patients with congenital cataracts gained an average of one Snellen line of best-corrected visual acuity; patients with traumatic cataracts lost an average of one Snellen line of best-corrected visual acuity. In older pediatric patients, epikeratophakia appears to be a safe and effective procedure for the correction of aphakia.

The nationwide study of epikeratophakia for aphakia in adults.

In the nationwide study of epikeratophakia, 154 ophthalmic surgeons who had attended a training course performed 519 procedures for the correction of aphakia in adults: 310 of the eyes had 30 or more days of follow-up after suture removal. Of 229 eyes, 172 (75%) were within 3 diopters of emmetropia after surgery. Of 259 eyes, 245 (95%) demonstrated improved uncorrected visual acuity; 138 (53%) improved by four or more Snellen lines. Of 265 eyes, 209 (78%) achieved within two lines or improved their best corrected visual acuity. Of the 119 patients who achieved or improved their preoperative best corrected visual acuity, 110 (92%) were within two Snellen lines or better by 30 to 60 days after suture removal. Of the 127 patients with more than three months of follow-up after suture removal, 124 (98%) of those between 18 and 70 years of age but only 13 of 23 (54%) of those between 81 and 87 years of age achieved within two lines or better of their best corrected visual acuity. Corneal astigmatism measured by keratometry changed from a preoperative mean (+/- S.D.) of 2.1 +/- 1.8 diopters to a postoperative mean of 2.7 +/- 2.6 diopters. Of the 519 tissue lenses, 22 (4%) were removed, and one third of these patients underwent a second, successful epikeratophakia procedure.

The nationwide study of epikeratophakia for aphakia in children.

In the nationwide study of epikeratophakia, 97 surgeons performed a total of 335 procedures in 314 eyes for the correction of aphakia in children under the age of 8 years 1 month. Fifteen children underwent bilateral surgery. Thirty-six tissue lenses were removed and 21 of these eyes underwent a second epikeratophakia procedure. Overall, the success rate for procedures was 89%, and with repeated surgery it was 95% for eyes. Seventy-three percent of the patients were within 3 diopters of emmetropia after surgery. Visual acuity results in patients able to provide verbal responses to the illiterate E, Allen card, or Snellen line chart testing showed improvement in most cases. The safety of epikeratophakia makes it a desirable option for the correction of aphakia in children who are spectacle or contact-lens intolerant, and the permanence of the correction eliminates the problem of optical noncompliance.

The nationwide study of epikeratophakia for myopia.

In the nationwide study of epikeratophakia, 116 ophthalmic surgeons performed 352 procedures for the correction of myopia; 256 of the eyes had 30 or more days of follow-up after suture removal. Of 204 eyes, 153 (75%) were within 30% of emmetropia after surgery. Of 208 eyes, 202 (97%) had postoperative best corrected visual acuity within two Snellen lines or better of their preoperative visual acuity. All but one patient improved uncorrected visual acuity. Of the 120 patients who equaled or improved their preoperative best corrected visual acuity, 116 (97%) were within two Snellen lines of their preoperative measurement between 30 and 60 days after suture removal. Corneal astigmatism changed from a preoperative mean (+/- S.D.) of 1.4 +/- 0.8 diopters to a postoperative mean of 2.6 +/- 2.1 diopters. Of 352 tissue lenses, 36 (10%) were removed, largely as a result of inaccurate power, decay, or failure to reepithelialize, and 17 of these eyes underwent a second successful epikeratophakia procedure.

A review of 1,147 cases of Sheets lens implantations.

A review of 1,147 Sheets Style 30 intraocular lens implantations is presented. The incidence of complications is similar to or less than that of J-loop lenses. In-the-bag placement appears to eliminate some of the problems associated with J-loop lenses placed in the ciliary sulcus.

The triple procedure: combined penetrating keratoplasty, extracapsular cataract extraction and lens implantation. An expanded experience.

The results of 177 triple procedures are presented from a continuous series of 197 cases recorded from 1973 to 1982. Eighty-nine percent achieved a visual acuity of 20/40 or better within a minimum followup period of six months. The complication rate was low, and usually managed medically. Subsequent major surgical procedures were required in only twelve (7%) of these cases (eight repeat keratoplasty, two retina repair, one resuture of graft incision, and one peripheral iridectomy). Subsequent minor surgical procedures were for discission of the posterior lens capsule in 50% of the medallion-style lens cases, and in 7% of the posterior chamber lens cases.

The triple procedure; combined penetrating keratoplasty, cataract extraction and lens implantation.

Results of combined keratoplasty, extracapsular cataract extraction and lens implantation (triple procedure) are reported for 67 eyes having at least 12 months follow-up. The average age of the patients was 73; the majority were female with a pre-op diagnosis of Fuchs's dystrophy. Post-op visual acuities were 20/40 or better in 72% of the eyes. No implants were removed and only one eye required regrafting. The discission rate was 32%; discissions were usually performed a year post-op. We feel the favorable results are due to uniform use of microsurgical extracapsular catarat extraction at the time of surgery with good capsular fixation of the lens implant.