Keratoconus detected by videokeratography in candidates for photorefractive keratectomy.

BACKGROUND: Patients with corneal shape abnormalities should be identified prior to photorefractive keratectomy (PRK). We used videokeratography screening to detect subclinical corneal abnormalities, including keratoconus, which might have been missed by conventional clinical evaluation. METHODS: One hundred forty-six apparently normal myopic eyes (-1.00 to -7.00 diopters [D] with less than 1.50 D of cylinder) of 91 consecutive patients who were candidates for PRK were screened by videokeratography. RESULTS: In 6 of 91 patients (7 of 146 eyes), unsuspected corneal shape abnormalities were detected by videokeratography. Two patients had definite keratoconus and three were classified as keratoconus suspects by inferior corneal steepening (Rabinowitz I-S index ranging from 1.62 to 6.20 D). One patient had early pellucid marginal degeneration. CONCLUSIONS: Keratoconus suspects and contact lens-induced changes resembling keratoconus are present in the "normal" myopic population that presents for refractive surgery. Videokeratographic screening is the only effective means of identifying these and other corneal shape abnormalities.

Results of excimer laser photorefractive keratectomy for the correction of myopia.

PURPOSE: This report summarizes the authors' 3-year experience with excimer laser photorefractive keratectomy on 240 eyes of 161 patients. METHODS: With constant laser emission parameters, nitrogen flow across the cornea was used on 79 eyes, whereas 161 eyes had no nitrogen flow. Of the 240 eyes, 74 were operated on without suction ring fixation. Postoperative pain management included patching and oral analgesics in 77 eyes and the use of topical diclofenac or ketorolac and a therapeutic soft contact lens in 163 eyes. Follow-up ranged from 1 month (206 eyes) to 36 months (10 eyes). RESULTS: At 3 months, 88% (144 eyes) had uncorrected visual acuity of 20/40 or better; 86% (151 eyes) had corrected visual acuity to within +/- 1 diopter of intended correction, and 10% (17 eyes) lost two or more lines of best-corrected visual acuity. At 12 months, 89% (122 eyes) achieved uncorrected visual acuity of 20/40 or better, 79% (115 eyes) had corrected visual acuity to within +/- 1 diopter of intended correction, and 4% (6 eyes) lost two or more lines of best-corrected visual acuity. At 24 months, 92% (44 of 48 eyes) had uncorrected visual acuity of 20/40 or better, 86% (44 of 51 eyes) had corrected visual acuity to within +/- 1 diopter of intended correction, and 5% (2 eyes) lost two or more lines of best-corrected visual acuity. At 36 months, 90% (9 eyes) achieved an uncorrected visual acuity of 20/40 or better, 90% (9 eyes) had corrected visual acuity to within +/- 1 diopter of intended correction, and no eyes lost two or more lines of best-corrected visual acuity. CONCLUSIONS: The results obtained with one procedure are within accepted standards of accuracy for refractive surgery, and there is the potential for refinement of the final optical correction. Complication rates are low and are not vision threatening. They included increased intraocular pressure, epithelial "map dot" changes, and recurrent corneal erosion syndrome, "central islands," and others. Photorefractive keratectomy appears to be a safe procedure over the short and medium term.

A retrospective study of disposable extended wear lenses in 100 patients: year 3.

We present the results of the third year of follow-up of a group of 100 patients wearing disposable contact lenses on an extended wear basis. Thirty-seven males and 63 females participated in the study. The mean patient age was 41.76 years (SD: 14.5), and the mean patient follow-up time was 37.73 months (SD: 5.25). Twenty-three patients were lost to follow-up. Most of those lost to follow-up decided to purchase their lenses at discount outlets. A case of recurrent corneal ulcers in a patient wearing lenses obtained from a discount outlet is described. A significant decrease in events defined as complications (14 events) was noted as compared with the second year (32 events) of the study. One corneal infiltrate and one corneal ulcer were noted. Disposable extended wear lenses may be a reasonable means of vision correction in the properly selected patient with appropriate follow-up provided by a well-trained eye care practitioner.

Effect of nitrogen flow on recovery of vision after excimer laser photorefractive keratectomy without nitrogen flow.

BACKGROUND: Excimer laser (VISX) photorefractive keratectomy was performed using nitrogen flowing through the ocular fixation ring. It was felt that eliminating nitrogen flow may provide faster early visual rehabilitation. METHODS: Two groups of 50 consecutive eyes underwent photorefractive keratectomy with (N2 flow) and without (no N2 flow) nitrogen flow, and were evaluated at 1 month postoperatively. RESULTS: There were more under- or overcorrections exceeding 1.00 diopter (D) in the N2 flow than in the no N2 flow groups. Eighteen eyes in the N2 flow and 11 in no N2 flow groups saw 20/50 or less, without correction. Fourteen eyes in the N2 flow and nine eyes in the no N2 flow groups lost two or more lines of best spectacle-corrected visual acuity. Four eyes in the N2 flow and none in the no N2 flow groups increased more than 1.00 D of astigmatism. CONCLUSION: The elimination of nitrogen flow in photorefractive keratectomy performed with the VISX laser appears to improve visual results in the early postoperative period.

A two-year experience with excimer laser photorefractive keratectomy for myopia.

PURPOSE: This report summarizes the authors' 2-year experience with excimer laser photorefractive keratectomy (PRK) on 160 eyes of 128 patients. METHODS: All eyes were treated with an excimer laser: fluence, 160 mJ/cm2; frequency, 5 Hz; ablation zone diameter, 5.0 to 5.5 mm; and depth per pulse, 0.21 to 0.27 microns. A suction fixation ring was used in all eyes either with nitrogen flow (79 eyes) or without nitrogen flow (81 eyes) across the cornea. Follow-up ranged from 1 month (152 eyes) to 24 months (12 eyes). RESULTS: At 3 months, 82% (139) of eyes achieved an uncorrected visual acuity of 20/40 or better; 83% were corrected to within +/- 1 diopter (D) of intended correction and 30% lost one line of best-corrected visual acuity. At 6 months, 88% (124) of eyes achieved an uncorrected visual acuity of 20/40 or better; 84% were corrected to within +/- 1 D of intended correction and 15% lost one line of best-corrected visual acuity. At 12 months, 91% (71) of eyes achieved an uncorrected visual acuity of 20/40 or better; 84% were corrected to within +/- 1 D of intended correction and 17% lost one line of best-corrected visual acuity. At 24 months, 100% (12) of eyes achieved an uncorrected visual acuity of 20/40 or better; 91.6% were within +/- 1 D of intended correction and 0% lost one line of best-corrected visual acuity. CONCLUSIONS: In eyes with a follow-up of 6 to 24 months, 77% to 100% achieved an uncorrected visual acuity of 20/40 or better and 84% to 92% were corrected to within +/- 1 D of the intended correction. The authors conclude that excimer laser PRK appears to be a safe procedure capable of correcting the eyes of patients with low to moderate myopia with approximately the same degree of accuracy as radial keratotomy.

A retrospective study of disposable extended wear lenses in 100 patients: year 2.

We present the results of the second year of follow-up of 100 patients wearing disposable contact lenses on an extended wear basis. Thirty-seven males and 63 females participated in the study (mean age: 41.1 years +/- 13.88 (mean +/- 1 standard deviation); and the mean patient follow-up time was 26 months +/- 4.9). A total of 13 patients were lost to follow-up. Seventeen patients discontinued extended wear yet continued to wear soft lenses on a daily wear basis--the reasons for this finding are discussed. A significant decrease in the number of events defined as complications (32 events) was noted when compared to the first year of follow-up (136 events). Seven corneal infiltrates occurred during the second year, compared to 6 such events during the first year of the study. Additional complications included: giant papillary conjunctivitis (6 cases), corneal staining (5 cases), and corneal abrasions (4 cases). Disposable extended wear soft contact lenses offer a reasonable means of vision correction in the properly selected patient. At the same time, caution should be exercised in the fitting and wear of these lenses.

The use of the SoftPerm lens for the correction of irregular astigmatism.

We evaluated the performance of the SoftPerm combined rigid gas permeable (RGP) and hydrogel lens for the visual correction of 49 eyes (30 patients) with irregular astigmatism. Follow-up was up to 15 months. An attempt was also made to compare the SoftPerm lens to its predecessor, the Saturn II lens. The most common etiology for irregular astigmatism was keratoconus. Others etiologies were penetrating keratoplasty and refractive surgery. Visual acuity improved significantly. Only two eyes were best corrected to 20/20 before fitting whereas, 13 eyes saw 20/20 after fitting. The rate of lens replacement was 0.22 lenses per eye per month. A variety of complications occurred, including corneal staining, abrasions, and edema. Complications also reflected the relative difficulty of handling of the lens, yet no vision threatening complications occurred. Overall, the SoftPerm lens is a vast improvement over the Saturn II and is a reasonable means of correction of irregular astigmatism.

One-year results of excimer laser photorefractive keratectomy for myopia.

BACKGROUND: Excimer laser photorefractive keratectomy for the correction of myopia is presently under investigation in the United States by the Food and Drug Administration (FDA). The Phase II-B FDA study is being conducted on 75 normally sighted myopic eyes utilizing three currently available excimer lasers. This report presents the 1-year results on 12 myopic eyes treated with the VISX excimer laser system at the Ellis Eye Center at Cedars-Sinai Medical Center in Los Angeles under the Phase II-B FDA protocol. METHODS: Twelve eyes of 12 patients with myopia between -1.75 and -5.00 diopters underwent 193 nm argon/fluoride excimer laser photorefractive keratectomy. The epithelium was mechanically removed, and fixation was accomplished with a suction ring which provided nitrogen flow across the corneal surface. The computer controlled corneal ablations were 5.00 mm in diameter and were accomplished with an iris diaphragm closing from large to small. RESULTS: The preoperative spherical equivalent myopia was -3.50 D (SD = 1.02) and the postoperative myopia was -0.25 (SD = 0.48). Eleven of the 12 patients achieved an uncorrected visual acuity of 20/30 or better and were corrected to within +/- 0.50 D of emmetropia. All corneas demonstrated a mild reticular subepithelial haze which was barely visible at 1 year. There were no vision-threatening complications and none of the eyes experienced a loss of best corrected visual acuity. CONCLUSIONS: In this small trial, the excimer laser appears to be capable of accurately changing the refractive power of the cornea for the correction of myopia with minimal side effects. Only when larger numbers of patients undergo the procedure will we be able to determine the safety and efficacy of photorefractive keratectomy as a refractive surgical procedure.

A retrospective study of disposable extended-wear lenses in 100 patients.

A retrospective evaluation of 100 patients who wore disposable extended-wear contact lenses is presented. The patients were selected at random and were fitted with one of three lens brands approved for extended wear. There were 37 males and 63 females in the study. The mean age was 40.1 years (range, 14 to 76 years). Sixty-seven of the patients wore nondisposable extended-wear soft contact lenses before being fitted with disposable lenses. Complications were noted and included two instances of infectious ulcerative keratitis and six cases of peripheral corneal infiltrates. It is believed that the rate of complications is due to the ongoing hypoxic effect of prolonged use of extended-wear or other contact lenses and may be improved by providing a greater variety of lens fitting parameters. Disposable extended-wear lenses may be a reasonable means of vision correction in the appropriately selected patient and with proper follow-up. At the same time, caution should be exercised in the fitting and wear of disposable extended-wear lenses.

Broken semiflexible intraocular lens implant.

The haptic of a semiflexible anterior chamber intraocular lens (Kelman Quadraflex) broke inside the eye of a 70-year-old man. No history of major eye or head trauma could be elicited from the patient. Clinical manifestations included inferior corneal edema progressing toward the optical axis resulting from a free-floating haptic segment of the lens implant inside the anterior chamber. A significant decrease in endothelial density was documented over a short period of time. The surgical management of this case included removal of the free-floating haptic segment, removal of the lens implant, penetrating keratoplasty, and vitrectomy. Final visual acuity was 20/70.

Combined use of sodium hyaluronate and tissue adhesive in penetrating keratoplasty of corneal perforations.

A new technique which allows the use of a guarded trephine in penetrating keratoplasty for corneal perforation is described. It involves the combined use of cyanoacrylate adhesive and sodium hyaluronate and allows a normotensive eye to be obtained prior to trephination. Five cases in which this technique was used are described. A better tectonic result can be obtained and visual rehabilitation may be more readily achieved without performing a secondary procedure.

Pseudophakic serous maculopathy.

A 73-year-old woman experienced a serous macular detachment following an uncomplicated planned extracapsular cataract extraction with placement of a posterior chamber intraocular lens with general anesthesia. To our knowledge, this complication of cataract surgery, with or without lens implantation, has not been previously reported. The specific cause of this chorioretinopathy is not clear. Breakdown of the retinal pigment epithelium-Bruch's membrane-choriocapillaris barrier due to surgical procedure would appear to be the most likely cause. The macular detachment gradually resolved, leaving the patient with excellent visual acuity.

Laser iridectomy treatment of acute pseudophakic pupillary block glaucoma.

A 71-year-old patient developed acute pupillary block glaucoma two years after uncomplicated extracapsular cataract surgery with primary implantation of a Choyce-style anterior chamber lens. He presented one week after the onset of pain. The attack was relieved with argon laser iridectomy. The presumed mechanism was rotation of the intraocular lens due to blunt trauma, occluding the previously patient single surgical iridectomy site. We felt that in this case, laser iridectomy was a good, safe alternative to surgical iridectomy.

Meibomian gland studies: comparison of steer and human lipids.

Simple surgery gave whole meibomian glands of steer yielding approximately 47 mg of lipid per pair of lids. This lipid gave a thin-layer chromatography pattern similar to that of steer or human excreta. Column chromatography of pooled steer gland lipids and pooled human lipid (excreta) gave 0.06% and 7.54% hydrocarbons, respectively, containing no squalene. Excluding human hydrocarbons (as exogenous material) the percentage composition of steer and human lipids were, respectively, sterol esters 31.7 and 29.5; wax esters 31.2 and 35.0; material in the diester region 11.4 and 8.4; triacyl glycerols 1.6 and 4.0; material in the post-triacyl glycerol region 2.8 and 3.2; free sterols 3.0 and 1.8; free fatty acids 5.1 and 2.1; and polar lipids 13.3 and 16.0. Glass capillary gas-liquid chromatography revealed the following: a series of normal odd- and even-chain hydrocarbons (C16 to C32) for the steer and a complex pattern for the human samples; unsubstituted fatty acids in total lipids and various lipid classes ranging from C12 to C31 with n-even, n-odd, iso-even and iso-odd, and anteiso-odd chains for both samples; and fatty alcohols in total lipids and wax esters ranging from C18 to C31. Anteiso structures predominated in the steer, and iso structures in the human samples. Steer fatty acids favored anteiso branching and saturation, whereas human acids favored iso branching and unsaturation. Fatty acids of sterol esters in both samples showed a wider range of chain lengths than did other lipid classes. Similarity of the fatty acid pattern suggests that the free fatty acids are derived from the triacyl glycerols as in human sebum. Identification of saturated fatty acids was confirmed by a gas liquid chromatography--mass spectrometry--data system (GLC-MS-DS). We define "meibum" and "meibocyte" as the meibomian gland equivalent of sebum and sebocyte.

Ocular pathology for clinicians. 8. Orbital cellulitis.

Orbital cellulitis secondary to sinusitis has been the most common cause of proptosis in children. A case report is presented which emphasizes that the signs and laboratory findings in orbital cellulitis may be confusing, especially when modified by prior antibiotics. When orbital cellulitis is a possibility, adequate antibiotic therapy should be instituted while diagnostic studies are being performed. CT scanning is a new and useful modality for the evaluation of these patients, but cautious and experienced interpretation is essential. In patients who do not respond promptly to appropriate medical therapy, surgical intervention is indicated for drainage and biopsy.

Experimental inflammatory serous detachment of the retina.

Rhesus monkey eyes were studied after the development of inflammatory serous retinal detachments following internal carotid artery injection of live, yeast-phase Histoplasma capsulatum organisms. Horseradish peroxidase (HRP) was used as a tracer to examine the inner and outer blood-retinal barriers. The HRP was present in a decreasing gradient from the choroid into the subretinal space and was not found to have leaked from retinal vessels. The source of subretinal fluid in this model of inflammatory serous retinal detachment was leakage from the choroid through a defective outer blood-retinal barrier, induced by disruption of the retinal pigment epithelium. This model has relevance to understanding the serous retinal detachments common to diseases affecting the choroid.

Variations in acute multifocal histoplasmic choroiditis in the primate.

Experimental histoplasmic choroiditis was produced in primates by intracarotid injections of living H. capsulatum organisms. The severity of the choroiditis varied with inoculum size, as well as with site of injection (common carotid vs. internal carotid artery). A reproducible model of histoplasmic choroiditis in primates was produced with an internal carotid injection of 5,000 to 10,000 organisms/lb. The clinical and histopathological course of this acute choroiditis over the first 30 days is presented.