Piggyback intraocular lens implantation.

The piggyback method of implanting two intraocular lenses in one eye has been successfully expanded to address pseudophakic refractive error in normal eyes and eyes that have undergone post-penetrating keratoplasty. Piggyback implantation has been combined with the use of newly available minus-power lenses to provide appropriate power for a cataract patient with keratoconus, as well as to correct pseudophakic myopia. The phenomenon of increased depth of focus in piggybacks may be explained by a contact zone between the lenses. The late complication of inter-lenticular cellular growth with resultant hyperopic shift, opacification, and loss of vision has recently become a concern.

Minus-power intraocular lenses to correct refractive errors in myopic pseudophakia.

PURPOSE: To evaluate the effectiveness of a secondary, piggyback, minus-power intraocular lens (IOL) to correct the refractive error in patients with myopic pseudophakia. METHODS: In this prospective noncomparative cohort study, 51 myopic pseudophakic patients received implantation of a minus-power IOL as a secondary procedure to correct residual pseudophakic myopia. RESULTS: The mean residual myopia of -3.05 diopters (D) was reduced to -0.38 D. All eyes were within +/- 1.00 D of the desired refraction. Uncorrected visual acuity was 20/40 or better in 72% of eyes, and best corrected visual acuity was 20/40 or better in 96%. Uncorrected visual acuity improved by 2 or more lines in 85% of eyes and by 5 or more lines in 65%. CONCLUSION: Clinical outcomes can now be improved in patients with myopic pseudophakia whose previous options (i.e., lens exchange or refractive surgery) were more traumatic or less predictable.

Refractive and visual outcome of hyperopic cataract cases operated on before and after implementation of the Holladay II formula.

OBJECTIVE: The primary objective was to evaluate the refractive and visual outcomes in a series of hyperopic cataract cases in which the Holladay II intraocular lens (IOL) power formula was used in conjunction with added eye measurements (measured anterior chamber depth [ACD], lens thickness, and corneal diameter) to improve predictability of refractive outcome. In addition, the impact of use of a double ("piggyback") IOL on refractive outcome was evaluated. DESIGN: Prospective, nonrandomized comparative clinical trial. PARTICIPANTS: A total of 136 consecutive hyperopic primary cataract-IOL cases operated on at in an outpatient eye surgery center were evaluated. The main inclusion criterion was the requirement of at least 30 D of emmetropia power. INTERVENTION: Implantation of a total implanted power calculated using a newly developed (Holladay II) formula, which uses additional eye measurements (measured ACD, lens thickness, corneal diameter) in addition to the axial length and keratometry normally used, was performed. In the first series, IOL powers were chosen using the Lloyd-Gills formula with modifiers; in the second series, powers were chosen using the Holladay II formula option in the Holladay IOL Consultant software. Selection criteria for both series were the same (requiring at least 30 diopters [D] of power for emmetropia). Keratometry and axial length measurements (by immersion) were taken using the same instrumentation and methodology in both series. Predicted postoperative refraction based on the IOL implanted and the method of power calculation used were computed for each case in both groups and compared to the actual achieved refraction. MAIN OUTCOMES MEASUREMENTS: Main clinical outcome parameters evaluated were the postoperative spherical equivalent (compared with the predicted spherical equivalent) and the best-corrected vision. These outcome parameters were evaluated within each surgical series, in the total group of cases (regardless of power calculation method). Further stratification according to the use of single or double implants also was done. RESULTS: In the group using an older formula system, mean preoperative spherical equivalent of 4.79 D was reduced to -0.67 D. Similarly, in the Holladay II group, the preoperative mean of 5.60 D was reduced to -0.58 D. However, there were fewer large deviations between predicted and achieved spherical equivalent in the Holladay II group as indicated by a smaller standard deviation of the absolute deviation (0.47 vs. 0.59), and the range of postoperative refractions was smaller with fewer large overcorrections or undercorrections. However, almost 90% of both groups were within a diopter of the predicted refraction. Visual results were comparable in the two groups. CONCLUSION: Both IOL calculation systems showed good predictability in these extremely short eyes. The Holladay II formula was simpler because it is incorporated into a user-friendly software package (Holladay IOL Consultant) and required only the input of IOL constants and preoperative measurements with no "fudge factor" modifiers. Results within the series using this formula had a tendency toward a smaller standard deviation with fewer outliers.

Radial keratotomy: a comprehensive evaluation.

A prospective clinical investigation of radial keratotomy employing the Fyodorov method and instrumentation was initiated in March, 1980. The results of the first 147 eyes undergoing this surgical procedure for the reduction or elimination of myopia were analyzed one year following surgery. The mean preoperative, uncorrected visual acuity was finger counting vision and the mean preoperative myopic spherical equivalent was 5.33 diopters. The preoperative myopic refractive error ranged from 1.75 to 11.75 diopters. Radial keratotomy resulted in a mean uncorrected visual acuity of 20/35 with a mean reduction on myopia of 4.66 diopters. Eighty percent of the 147 eyes experienced 20/40 or better uncorrected vision. Sixty-eight percent of high myopia eyes (6.00 to 11.75 D) attained this level of uncorrected vision with a mean reduction of myopia of 6.23 diopters. Glare and variation of vision were the most frequently reported complications. A non-progressive endothelial cell loss of 5.2 percent was observed. The degree of preexisting myopia, patient age, fellow eye experience and surgeon learning curve significantly influenced the surgical result and facilitated the predictability of the procedure. Incision depth was directly related to surgical result. The low myopia group achieved stabilization of effect by six months while stabilization occurred later in patients with high degrees of initial myopia. Patient satisfaction was high and 78 per cent of the patients elected to undergo radial keratotomy in their fellow eye.

Surgical correction of high postkeratoplasty astigmatism. Relaxing incisions vs wedge resection.

Improved techniques and procedures have resulted in a higher rate of clear grafts after penetrating keratoplasty. A clear graft, however, does not give a good visual result if high corneal astigmatism prevents the successful wearing of spectacles or contact lenses. This article describes the methods and results of two microsurgical techniques--the corneal wedge resection to steepen the flat meridian and relaxing incisions to flatten the steep meridian. Average reduction in corneal astigmatism was greater for the wedge resection (ten cases) (6.50 diopters as compared with 4.25 D [16 cases] for the relaxing incisions). The relaxing incisions operation was successful in 75% of cases with stabilization of corneal curvature readings in an average of three weeks and is an outpatient procedure. After a wedge resection, corneal stabilization usually takes months. We believe that wedge resection should be reserved for cases in which relaxing incisions are unsuccessful.

Reticular dystrophy of the retinal pigment epithelium. A clinical and electrophysiologic study of three generations.

Reticular dystrophy of the retinal pigment epithelium is characterized by a posterior pattern of pigment clumping like a "fishnet with knots." Four patients in three successive generations were seen with typical reticular dystrophy. A fifth patient had abnormal dark adaptation. In this family reticular dystrophy was characterized by the typical reticular pigmentary pattern, good visual acuity, normal electroretinographic findings, abnormal electro-oculographic findings, and abnormal dark adaptation. The pedigree indicates autosomal dominance as the inheritance pattern.