Refractive results of phacoemulsification in vitrectomized patients

The LISA-PPV Formula: An Ensemble Artificial Intelligence-Based Thick Intraocular Lens Calculation Formula for Vitrectomized Eyes

PURPOSE

To investigate the relationship between effective lens position (ELP) and patient characteristics, and to further develop a new intraocular lens (IOL) calculation formula for cataract patients with previous pars plana vitrectomy (PPV).

DESIGN

Cross-sectional study.

METHODS

A total of 2793 age-related cataract patients (group 1) and 915 post-PPV cataract patients (group 2) who underwent phacoemulsification with IOL implantation were included. The ELP of 2 groups was compared and the association between ELP and patient characteristics was further evaluated using standardized multivariate regression coefficients. An ensemble artificial intelligence-based ELP prediction model was developed using a training set of 810 vitrectomized eyes, and a thick-lens IOL formula (LISA-PPV) was constructed and compared with 7 existing formulas on an external multi-center testing set of 105 eyes.

RESULTS

Compared to eyes with age-related cataract, vitrectomized eyes showed a similar ELP distribution (P = .19), but different standardized coefficients of preoperative biometry for ELP. The standardized coefficients also varied with the type of vitreous tamponade, history of scleral buckling, and ciliary sulcus IOL implantation. The LISA-PPV formula showed the lowest mean and median absolute prediction error (MAE: 0.63 D; MedAE: 0.44 D), and the highest percentages of eyes within ±0.5 D of prediction error (57.14%) in the testing dataset.

CONCLUSIONS

The ELP prediction required optimization specifically for vitrectomized eyes based on their biometric and surgical characteristics. The LISA-PPV formula is a useful and accurate tool for determining IOL power in cataract patients with previous PPV (available at http://ppv-iolcalculator.com/).

Change in refraction, corneal power and axial length of the eye secondary to silicone oil tamponade injection after pars plana vitrectomy

Background: Refractive and ocular biometric changes after silicone oil tamponade (SOT) in phakic eyes have been studied thoroughly; however, similar studies amongst Sudanese patients with vitreoretinal conditions were not carried out.Aim: This study aimed to assess post-operative changes in refraction, corneal power and axial length after pars plana vitrectomy (PPV) with SOT in phakic patients.Setting: The study was conducted at Sudan Eye Center, Khartoum, Sudan.Methods: A cross-sectional retrospective hospital-based study was performed at Sudan Eye Center. The study included all phakic patients who underwent PPV with SOT for a variety of vitreoretinal conditions from October 2018 to January 2019. Clinical investigations included uncorrected visual acuity (VA), best-corrected VA, refraction, corneal power and axial length pre- and post-surgery. Differences in these parameters were assessed using a paired sample t-test with a significance level of 0.05.Results: Medical records of 59 consecutive patients (59 eyes, 41 men and 18 women) with ages ranging from 22 years to 75 years were studied. The findings revealed a statistically significant hypermetropic change (pre: –0.17 ± 2.44 dioptre [D] and post: +4.43 ± 2.04 D) with a p-value of 0.001. In terms of axial length, there was a significant increase (pre: 23.61 ± 1.17 mm and post: 23.82 ± 1.27 mm; p  0.001). However, no significant change was found in corneal power (pre: –43.60 ± 1.96 D and post: 43.63 ± 2.03 D; p = 0.45).Conclusion: A hypermetropic shift in refraction, longer axial length and non-considerable increase in corneal power were observed amongst Sudanese phakic patients after PPV with instillation of silicone oil.

Cataract Following Pars Plana Vitrectomy: A Review

Introduction: The indications for pars plana vitrectomy (PPV) have increased over the years. The vitreous is no longer considered an inert ocular structure and it is well known that its removal has anatomical and physiological consequences. The vitreous is no longer considered an inert ocular structure. The vitreous plays a key role as an intraocular physiologic oxygen regulator. In order to maintain its transparency, the crystalline lens needs protection from an excessive oxygen exposure. PPV leads to progression of nuclear sclerosis in most eyes.Methods: A systematic review of the literature was conducted using Embase and Medline databases. Articles studying the physiology, pathogenesis and surgical treatment of cataract after PPV were included in this review.Results: The pathogenesis of cataract formation after PPV remains unclear. Predisposing factors include advanced patient age, preexisting nuclear sclerosis, light toxicity, intraoperative oxidation of lens proteins, use of silicone oil or intravitreal gas, mechanical trauma and the duration of exposure to an irrigating solution.Conclusion: Cataract surgery in vitrectomized eyes presents with more technical difficulties, is more challenging and often has a higher risk of intraoperative and postoperative complications than in non vitrectomized eyes. There is no standardized technique or management in these cases; therefore, it requires more precautions during surgery.

Phacoemulsification outcomes and complications in vitrectomised versus non-vitrectomised eyes

Clinical relevance: Pars plana vitrectomy techniques have evolved in the recent years and the number of patients undergoing phacoemulsification for post-vitrectomy cataract has increased. Eye-care practitioners need to be aware of intraoperative complications and post-operative outcomes in previously vitrectomised eyes.Background: The aim of the present study is to compare the outcomes and related complications of phacoemulsification in previously vitrectomised versus non-vitrectomised eyes.Methods: This is a retrospective case-control study. Visual acuity, refractive outcomes, intra- and post-operative complications were analysed in consecutive phacoemulsification patients between January 2015 and August 2017. Patients with no post-operative data were excluded.Results: One hundred and forty-nine previously vitrectomised eyes and 608 non-vitrectomised eyes were included in the analysis. Previous pars plana vitrectomy was associated with worse logMAR visual acuity pre-operatively (0.75 ± 0.54 vs. 0.40 ± 0.33, p < 0.0001) and post-operatively (0.15 ± 0.29 vs. 0.09 ± 0.22, p = 0.014). There were no statistically significant differences between the two groups regarding refractive outcomes (p = 0.393) or posterior capsule rupture rate (p = 0.223). Previous pars plana vitrectomy was associated with a higher risk of post-operative macular oedema (p = 0.046) and posterior capsule opacification (p < 0.0001).Conclusions: Previous pars plana vitrectomy was not associated with a higher risk of intraoperative complications. However, a higher incidence of cystoid macular oedema and posterior capsule opacification were identified in the present study. Further research can provide insight into the mechanisms involved and any appropriate prevention strategies for these conditions.

Refractive Outcomes and Anterior Chamber Depth after Cataract Surgery in Eyes with and without Previous Pars Plana Vitrectomy

Purpose: To compare the differences in refractive outcome and anterior chamber depth (ACD) after phacoemulsification between eyes with and without previous pars plana vitrectomy (PPV).Materials and Methods: Patients who had significant cataracts after PPV were included in the study group, and patients with a matched axial length (AL) who had cataracts without PPV were selected as the control group. The performance of new generation intraocular lens (IOL) power calculation formulas (Barrett Universal II, Kane, Ladas Super formulas), and the traditional formulas (SRK/T, Holladay 1, Hoffer Q, Haigis) with and without the Wang-Koch (WK) AL adjustment were compared between the two groups. The postoperative ACD was measured using the Scheimpflug imaging system with manual correction at least three months after surgery. Results: In total, there were 193 eyes from 193 patients in each group. The mean prediction errors (MEs) of the new generation formulas had no significant systemic bias in the study group; the hyperopic shift was displayed in the traditional formulas for eyes with AL > 26mm. However, the difference of MEs between the two groups among all the formulas were not significant. The absolute prediction error (MAE) and median prediction error (Med AE) in the study group were larger than those in the control group among all the formulas. The postoperative ACD of the study group was deeper but not significant than that of the control group. Conclusions: There was no refractive shift in vitrectomized eyes compared with non-vitrectomized eyes no matter in new generation formulas or traditional vergence formulas. The prediction error among all the formulas in vitrectomized eyes were significantly higher than those in non-vitrectomized eyes. The ACD after phacoemulsification in vitrectomized eyes was not significantly different from non-vitrectomized eyes.

Cataract surgery of eyes with previous vitrectomy: risks and benefits as reflected in the European Registry of Quality Outcomes for Cataract and Refractive Surgery

PURPOSE

To explore the frequency and outcomes of cataract surgery in eyes with previous vitrectomy.

SETTING

Fifteen European countries.

DESIGN

Retrospective cross-sectional register-based study.

METHODS

The European Registry of Quality Outcomes of Cataract and Refractive Surgery (EUREQUO) contains data on baseline characteristics, surgery, and follow-up for cataract surgeries. Previous vitrectomy is included as a mandatory parameter in baseline characteristics. According to the protocol for EUREQUO, consecutive cases should be reported by participating units.

RESULTS

This study included data from units in 15 European countries from 2008 to 2018; 1 715 348 cataract extractions with follow-up data were reported to EUREQUO. Previous vitrectomy was reported in 19 416 eyes comprising 1.1% of all cases. This proportion was about the same for each study year. Most patients were men, and their mean age was 64.1 years compared with 73.7 years for the rest of the database. The preoperative visual acuity was modestly worse in postvitrectomy eyes compared with the opposite (corrected distance visual acuity [CDVA] 0.45 vs 0.25, respectively). A postoperative CDVA of 0.5 or better was achieved by 82.8% of the postvitrectomy eyes compared with 95.6% for the non-postvitrectomy eyes. The absolute mean biometry prediction error for the same groups was 0.52 diopters (D) vs 0.43 D, respectively.

CONCLUSIONS

Patients undergoing cataract extraction after previous vitrectomy were younger and mostly men. Their visual and refractive outcomes were slightly inferior compared with the patients without vitrectomy.

A comparative study of lens management in the United Kingdom and India with regard to rhegmatogenous retinal detachment surgery

INTRODUCTION

Lens management in phakic patients with rhegmatogenous retinal detachments undergoing para plana vitrectomy surgery remains controversial among vitreoretinal surgeons. When combined phacovitrectomy is performed, the biometry decisions can be challenging both in the face of macula-off rhegmatogenous retinal detachments and previous refractive surgery. This study analyses current trends in practise.

METHODS

A scenario-related survey was sent to all members of the British and Eire Association of Vitreoretinal Surgeons and to vitreoretinal surgeons in the northern Indian state of Punjab.

RESULTS

In post-laser-assisted in situ keratomileusis patients with a visually significant cataract and a macula-on rhegmatogenous retinal detachment, the majority of British and Eire Association of Vitreoretinal Surgeons members (67.3%) and surgeons in Punjab (91.4%) would perform a stand-alone para plana vitrectomy and defer cataract surgery. When a combined phacovitrectomy is performed in this scenario, the majority of British and Eire Association of Vitreoretinal Surgeons (68%) would implant an intraocular lens (using either Haigis-L or European Society of Cataract and Refractive Surgeons/American Society of Cataract and Refractive Surgeons calculators), whereas the majority of Punjab surgeons (79.3%) would leave the patient aphakic. In a patient with a cataract and macula-off rhegmatogenous retinal detachment undergoing combined phacovitrectomy surgery, without any previous refractive surgery, the majority of British and Eire Association of Vitreoretinal Surgeons members (47.3%) would use the opposite eye biometry, whereas most Punjab surgeons (62.7%) would leave the patient aphakic.

DISCUSSION

Vitreoretinal surgeons in both the United Kingdom and Punjab predominantly avoid combined surgery in rhegmatogenous retinal detachment cases, even when faced with a visually significant cataract. When combined phacovitrectomy is performed, most vitreoretinal surgeons preference using the opposite eye biometry for macula-off cases and Haigis-L (myope) or online calculators for post-laser-assisted in situ keratomileusis cases.