Open ring-shaped guider for circular continuous curvilinear capsulorhexis during cataract surgery

Evaluation of continuous curvilinear capsulorhexis based on a neural-network

PURPOSE

Continuous curvilinear capsulorhexis (CCC), as a prerequisite for successful cataract surgery, is one of the most important and difficult steps in phacoemulsification. In clinical practice, the size and circularity of the capsular tear and eccentricity with the lens are often employed as indicators to evaluate the effect of CCC.

METHODS

We present a neural network-based model to improve the efficiency and accuracy of evaluation for capsulorhexis results. The capsulorhexis results evaluation model consists of the detection network based on U-Net and the nonlinear fitter built from fully connected layers. The detection network is responsible for detecting the positions of the round capsular tear and lens margin, and the nonlinear fitter is utilized to fit the outputs of the detection network and to compute the capsulorhexis results evaluation indicators. We evaluate the proposed model on an artificial eye phantom and compare its performance with the medical evaluation method.

RESULTS

The experimental results show that the average detection error of the proposed evaluation model is within 0.04 mm. Compared with the medical method (the average detection error is 0.28 mm), the detection accuracy of the proposed evaluation model is more accurate and stable.

CONCLUSION

We propose a neural network-based capsulorhexis results evaluation model to improve the accuracy of evaluation for capsulorhexis results. The results of the evaluation experiments show that the proposed results evaluation model evaluates of the effect of capsulorhexis better than the medical evaluation method.

Advances in capsulorhexis

PURPOSE OF REVIEW

Continuous curvilinear manual capsulorhexis is currently the standard of cataract surgery. In the past several years, new technologies have been developed to improve the consistency and safety of capsulorhexis creation. This article reviews the most recent technologies in capsulotomy formation and their advantages and disadvantages.

RECENT FINDINGS

Guidance devices, femtosecond laser capsulotomy and precision pulse capsulotomy improve the centration, circularity and precision of anterior capsulorhexis and capsulotomy. These developments show particular promise for complex cataract surgeries, though clinical data on the refractive outcomes and complication rates of these technologies are currently limited and warrant additional investigation.

SUMMARY

New technological advances in capsulorhexis help surgeons achieve a more ideal capsulotomy geometry. Whether this translates into more predictable refractive outcomes and safer surgeries remains an area of future study.

Clinical results of the open ring PMMA guider assisted capsulorrhexis in cataract surgery

Background

To compare the results of continuous curvilinear capsulorrhexis(CCC) after application of an open ring-shaped guider compared with a free-hand procedure in eyes with cataracts.

Methods

This study comprised patients undergoing cataract surgery in Seoul St.Mary’s Hospital, The Catholic University of Korea. Eyes were grouped depending on the capsulotomy method; CCC was performed by free-hand procedure on 94 eyes (free-hand group), and it was performed under the guidance after introduction of an open ring-shaped guider on consecutive 89 eyes (guided group). Horizontal and vertical diameter, area and circularity of capsulotomy were measured postoperatively at one day, two months and six months. Differences in parameters and the percentage of ideal capsulorrhexis were analyzed between the two groups.

Results

On the first postoperative day, the vertical diameter in the guided group (5.24 ± 0.16 mm) was significantly longer than that of the free-hand group (5.01 ± 0.65 mm, P = 0.019). The area of capsulotomy was larger in the guided group (21.55 ± 0.87 mm²) than that of the free-hand group (20.34 ± 2.96 mm², P < 0.001). Circularity in the guided group (0.84 ± 0.03), was significantly greater than that of the free-hand group (0.69 ± 0.17, P = 0.036). Ideal capsulorrhexis was obtained in 60 eyes (67%) in the free-hand group and 81 eyes (86%) in the guided group.

Conclusions

After introduction of an open ring-shaped guider, CCC became larger and more circular with less anterior capsular contracture. The rate of acquiring ideal capsulorrhexis was higher in the guided group than it was in the free-hand group for six months after surgery.

Effect of number and position of intraocular lens haptics on anterior capsule contraction: a randomized, prospective trial

BACKGROUND

The present study aimed to evaluate the degree of anterior capsule contraction (capsulorhexis contraction) with three different single-piece, hydrophilic acrylic intraocular lenses (IOLs).

METHODS

Patients were prospectively randomized to be implanted with one of three types of IOLs during cataract surgery: the Ophtec Precizon (IOL A), the Lucid Korea Microflex (IOL B), and the Carl Zeiss Asphina (IOL C). One week, 2 weeks, and 6 months after surgery, the area of the anterior capsule opening was measured using digital retro-illumination images after dilation of the pupil. The data were then evaluated using POCOman software.

RESULTS

The study included 236 eyes of 202 patients. The area of the anterior capsule opening reduced by 3.53 ± 3.31 mm (17.06% ± 15.99%) between 1 week and 2 months post-operatively in the IOL A group, by 0.62 ± 1.32 mm (2.87% ± 6.03%) in the IOL B group, and by 1.09 ± 1.53 mm (4.72% ± 6.10%) in the IOL C group. The IOL B group showed minimal anterior capsule contraction 2 months after surgery (p < 0.001).

CONCLUSIONS

IOLs with a four-plate haptic design (IOL B) showed more anterior capsular stability than those with a two-loop plate haptic (IOL A) or two-plate haptic (IOL C) design. The number and position of haptics in a capsular bag may affect anterior capsule contraction. We assume that supporting the zonules evenly may play a role in anterior capsular stability.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN76566080 , Retrospectively registered (Date of registration: 14 Feb 2018).