Reply: Cataract surgery and microphthalmic eyes

Refractive outcomes in nanophthalmic eyes after phacoemulsification and implantation of a high-refractive-power foldable intraocular lens

PURPOSE

To evaluate the refractive and postoperative outcomes of a high-power foldable intraocular lens (IOL) in nanophthalmic eyes.

SETTING

Six ophthalmic surgical centers in Canada.

DESIGN

Retrospective case series.

METHODS

Consecutive charts of nanophthalmic patients having cataract extraction and insertion of the CT Xtreme D IOL were reviewed. Demographic and clinical data were collected, including age, sex, axial length (AL), minimum keratometry (K) value and maximum K value, corneal white-to-white (WTW), anterior chamber depth, lens thickness (LT), and complications. The following preoperative and operative data were collected: uncorrected distant visual acuity (UDVA), corrected distant visual acuity (CDVA), sphere, cylinder, and spherical equivalence (SE). The primary outcome measure was change in SE. The secondary outcome measures were changes in UDVA and CDVA.

RESULTS

A total of 21 eyes from 13 patients with a mean follow-up time of 9.6 ± 8.5 months were studied. Mean preoperative data were: age (51.4 ± 15.2 years), AL (16.63 ± 0.68 mm), minimum K value (46.20 ± 2.26 D), maximum K value (47.55 ± 2.34 D), anterior chamber depth (2.60 ± 0.49 mm), WTW (11.08 ± 1.38 mm), LT (4.70 ± 0.97 mm), and IOL power implanted (+49.9 ± 3.3 diopters [D]). SE improved from +16.11 ± 3.26 D preoperatively to +2.00 ± 2.37 D postoperatively (P < .0001). UDVA improved from 1.47 ± 0.30 logMAR preoperatively to 0.74 ± 0.43 logMAR postoperatively (P = .016). CDVA did not change significantly. Five eyes (23.8%) had serious postoperative complications. Of these eyes, 2 had malignant glaucoma, 2 had vitreous hemorrhages, and 1 eye had a vitreous hemorrhage with retinal detachment resulting in visual acuity of no light perception.

CONCLUSION

Implanting foldable high-power IOLs in a series of nanophthalmic eyes yielded significant improvement in UDVA and SE. Cataract surgery in these eyes carries increased risk.

FINANCIAL DISCLOSURE

Iqbal Ike K. Ahmed is a consultant to Carl Zeiss Meditec AG. No other author has a financial or proprietary interest in any material or method mentioned.

Analysis of the Optical Quality of Spherical and Aspheric Intraocular Lenses in Simulated Nanophthalmic Eyes

PURPOSE

To analyze the optical performance of different implant strategies in simulated nanophthalmic eyes.

METHODS

An optical design software was used. Analysis included eye models that required 30.00, 45.00, and 60.00 diopters (D) intraocular lenses (IOLs) to achieve emmetropia. Spherical and aspheric IOLs were designed. They were tested either with a single implant setting S or by splitting the power into two lenses. Setting P1 had an even split of the power between the lenses and setting P2 had an uneven power split with one-third of the power in the anterior lens and two-thirds in the posterior IOL. The area under the modulation transfer function (MTF) curve was calculated and spherical aberration was recorded in each setting.

RESULTS

Setting S had the worst optical performance in the spherical group and the best performance in the aspheric group. A statistically significant difference was found between setting S and the piggyback options (settings P1 and P2) in all analyzed variables for the spherical and aspheric groups for the 45.00 and 60.00 D IOL requirement. No statistically significant difference was found between the piggyback settings.

CONCLUSIONS

Single aspheric IOLs had better optical performance than piggybacking lower-power aspheric IOLs. In the spherical lenses group, the results were the opposite, with the piggyback options having higher optical quality than the single IOL. MTF shows that single aspheric lenses provide the highest contrast sensitivity among all of the analyzed settings.

Accuracy of the refractive prediction determined by multiple currently available intraocular lens power calculation formulas in small eyes

PURPOSE

To observe the refractive outcomes of cataract surgery in small adult eyes, and to investigate the accuracy of different intraocular lens (IOL) power prediction formulas.

DESIGN

Retrospective interventional case series.

METHODS

We included consecutive small eyes undergoing uneventful phacoemulsification cataract surgery with a single highly powerful IOL (Acrysof SA60AT) implanted in the capsular bag (range of powers +35.0 to +40.0 diopters [D]), at the Cataract Centre for Moorfields Eye Hospital. Exclusion criteria were combined or previous intraocular surgical procedures, and any type of intraoperative complications. Main outcome measures were mean prediction errors with Hoffer Q, Holladay 1, Holladay 2, Haigis, SRK-T, and SRK-II IOL power prediction formulas and proportions of eyes achieving absolute errors within the dioptric ranges of 0.5, 1.0, and 2.0 D of target and emmetropia, respectively. The ANOVA test was used to compare the refractive results among various formulas.

RESULTS

Twenty-eight eyes were studied; the mean numerical error was 0.22 ± 1.22 D and the mean absolute error was 0.95 ± 0.78 D with the adopted Hoffer Q formula; 39%, 61%, and 89% of the eyes had a final refraction within 0.5 D, 1.0 D, and 2.0 D of target, respectively. None of the latest-generation formulas significantly outperformed the others (P = .245).

CONCLUSIONS

The Hoffer Q formula led to good or fair refractive outcomes in less than two thirds of the cases. With Holladay 1 and 2 and Haigis formulas, outcomes would have not been significantly different. The SRK formulas yielded less accurate predictions. Possible reasons are discussed.

Cataract surgery in small adult eyes

AIM

To evaluate the clinical outcomes of phacoemulsification cataract surgery in microphthalmos.

METHODS

Retrospective consecutive case series of eyes with axial length <20.9 mm, and requiring a high intraocular lens (IOL) power (≥30 or ≥35 dioptres for anterior or posterior chamber fixation, respectively), with no history of previous ocular surgery, and undergoing planned phacoemulsification cataract surgery with IOL implantation at Moorfields Eye Hospital was investigated to observe the incidence of intraoperative and postoperative complications.

RESULTS

During a 5-year study period, 47 of 22,093 eyes were treated in two locations (0.21%). Thirty-nine eyes met the study inclusion criteria. No serious intraoperative adverse events were recorded. Severe postoperative complications (retinal detachment and chronic postoperative uveitis) occurred in two cases. The postoperative corrected distance visual acuity (CDVA) was logMAR 0.30 or better in 24 eyes (62%), and only three eyes obtained worse vision. The overall ocular comorbitidy rate was 53%; 10 microphthalmic eyes (26%) presented with associated congenital or hereditary pathology, and had worse visual outcomes (p<0.0001).

CONCLUSIONS

Microphthalmic eyes requiring high IOL power are rare, and their presence is often associated with other ocular congenital or acquired disorders. Overall, the clinical outcomes were satisfactory and the surgical procedure affected by a low complication rate.