Changes in refraction and axial length according to the viscosity of intraocular silicone oil

Refractive outcomes following silicone oil tamponade in vitreoretinal surgery

PURPOSE

To evaluate the factors influencing the refractive outcomes following silicone oil tamponade (SOT) and silicone oil removal (SOR) in different lens statuses post-vitreoretinal surgery.

DESIGN

Retrospective analysis of three different lens statuses.

MATERIALS AND METHODS

This was a descriptive study that included 150 eyes of 147 patients who had undergone pars plana vitrectomy with SOT and SOR between January 2017 and June 2021. Demographic profile, spherical equivalent refraction (SER), and its association with clinical features were evaluated with SOT and post-SOR.

RESULTS

The mean (±standard deviation [SD]) age was 47 ± 17.8 years, including all three groups. SER was represented in diopters (D). The mean ± SD refraction with SOT in phakic, pseudophakic, and aphakic was 4.28 ± 2.59 D, 2.94 ± 2.58 D, and 3.98 ± 4.82 D. The mean SER post-SOR in phakic, pseudophakic, and aphakic was -2.72 ± 2.03 D, -1.12 ± 1.41 D, and 8.22 ± 3.70 D. The diagnosis of rhegmatogenous retinal detachment (RRD) among 96 eyes (64%) is the common indicator to perform vitreoretinal (VR) surgery. A minority of subjects were managed with retinal lasers before VR surgery (14%). The macula was attached in 100 eyes (67.6%), the belt buckle was done in 37 eyes (24.7%), and the silicone oil viscosity with 1000 centistoke was chosen in 129 eyes (86%).

CONCLUSION

SOT was used as a tamponade in VR surgeries irrespective of lens status. The significant predictor for post-SOR refraction in phakic and aphakic is post-SOT refraction. In pseudophakic, gender and diagnosis of RRD are the predictors of SOR refraction.

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.

Measurement of crystalline lens tilt in high myopic eyes before cataract surgery using swept-source optical coherence tomography

Background

To measure the crystalline lens tilt in eyes with various degrees of myopia before cataract surgery using swept-source optical coherence tomography (SS-OCT).

Methods

We used SS-OCT (IOLMaster 700) to scan 131 emmetropic eyes (axial length < 24.5 mm), 25 mild/moderate myopic eyes (axial length 24.5-26 mm), and 123 high myopic eyes (52, 29, and 42 eyes with axial lengths of 26-28, 28-30, and > 30 mm, respectively) as part of the routine preoperative examination before cataract surgery. SS-OCT involved B-scans along six meridians. The data were analyzed to assess the magnitude and orientation of the lens tilt and their correlation with other optical biometric parameters.

Result

The mean tilt was 3.36 ± 0.98° in emmetropic eyes, 3.07 ± 1.04° in mild/medium myopic eyes, and 2.35 ± 1.01° in high myopic eyes. Tilt correlated significantly and inversely with axial length (Pearson's r = - 0.427, P < 0.001). The crystalline lens tilt predominantly faced the upper outer quadrant relative to the visual axis, symmetrically in both eyes, with mean angles of 24.32° and 147.36° in the right and left eyes, respectively. The variability in the lens tilt direction increased with increasing axial length (χ² test, P < 0.001).

Conclusion

The magnitude of crystalline lens tilt decreased with increasing axial length. The direction of tilt was predominantly towards the upper outer quadrant in both eyes. The variability in the tilt orientation increased with increasing axial length.

Trial registration

NIH (clinicaltrial.gov), NCT03062085. Registered 23 February 2017.

Refractive state following retinal reattachment and silicone oil tamponade in dogs

OBJECTIVE

To evaluate the refractive error induced by intraocular administration of silicone oil (SiO) in dogs.

ANIMALS

47 client-owned dogs evaluated for blindness secondary to retinal detachment.

PROCEDURES

-3-port pars plana vitrectomy with perfluoro-octane and SiO exchange (1,000- or 5,000-centistoke SiO) was performed in 1 or both eyes for all dogs (n = 63 eyes), depending on which eye or eyes were affected. Dogs were normotensive, had complete oil filling of the eyes, and were examined in a standing position for retinoscopic examination of both eyes (including healthy eyes).

RESULTS

The mean refractive error for SiO-filled phakic and pseudophakic eyes was 2.67 and 3.24 D, respectively. The mean refractive error for SiO-filled aphakic eyes was 6.50 D. Dogs in which 5,000-centistoke SiO was used had consistently greater positive refractive errors (mean, 3.45 D), compared with dogs in which 1,000-centistoke SiO was used (mean, 2.10 D); however, the difference was nonsignificant. There was no significant linear relationship between refractive error and the number of days between surgery and retinoscopy.

CONCLUSIONS AND CLINICAL RELEVANCE

Hyperopia was observed in all dogs that underwent SiO tamponade, regardless of lens status (phakic, pseudophakic, or aphakic). Aphakic eyes underwent a myopic shift when filled with SiO. Pseudophakic eyes appeared to be more hyperopic than phakic eyes when filled with SiO; however, additional investigation is needed to confirm the study findings.

Refractive status and visual acuity changes after oil removal in eyes following phacovitrectomy, intraocular lens implantation, and silicone oil tamponade

OBJECTIVE

To examine the refractive changes in pseudophakic eyes with silicone oil tamponade (SOT) and removal.

DESIGN

Retrospective review.

PARTICIPANTS

Twenty-six consecutive eyes (23 patients) that had undergone phacovitrectomy, posterior chamber intraocular lens (IOL) implantation, and SOT by a single surgeon.

METHODS

Phacoemulsification and biconvex-type foldable acrylic IOLs were implanted. A standard 3-port pars plana vitrectomy was performed using a 20-gauge vitrectomy system. Following fluid-air exchange, 1300 centistokes silicone oil (SO) was injected. Manifest refractions with SOT and after SO removal were performed using best-spectacle correction based on retinoscopy results at least 1 month after each surgery.

RESULTS

A mean spherical equivalent of 3.85 (SD 1.63) diopters (D) and logMAR best-corrected visual acuity (BCVA) of 0.77 (SD 0.50) were observed with SOT. After SO removal, a myopic shift of -4.51 (SD 1.79) D was observed, resulting in -0.66 (SD 1.40) D, which concurred with the preoperative target of -0.47 (SD 0.50) D (p = 0.465, paired t test) and logMAR BCVA of 0.65 (SD 0.52) (p = 0.131, paired t test). Multivariate linear regression analysis demonstrated that the axial length and refractive index of the IOL were significant factors in determining refraction in oil-filled pseudophakia (p = 0.000).

CONCLUSIONS

Phacovitrectomy, IOL implantation, and SOT resulted in a tolerable range of hyperopia and visual acuity comparable to that after SO removal.

Refractive changes in silicone oil-filled pseudophakic eyes

PURPOSE

We examined the refractive changes in pseudophakic eyes of patients with idiopathic macular hole treated with silicone oil injection.

METHODS

Twenty consecutive eyes of 19 patients with idiopathic macular hole who had undergone successful pars plana vitrectomy using silicone oil tamponade were studied retrospectively. Lensectomy with intraocular lens (IOL) implantation was performed on each patient before vitreous surgery. Five biconvex type IOL models were used. After pars plana vitrectomy and fluid-air exchange, silicone oil was injected to replace the air completely. Macular hole closure was confirmed by optical coherence tomography, and silicone oil removal was performed. Manifest refractions before silicone oil filling, with silicone oil filling, and after silicone oil removal were determined.

RESULTS

A mean hyperopic shift +/- SD in spherical equivalents of +5.69 +/- 1.71 diopters (P < 0.0001) was observed with silicone oil instillation. In contrast, a mean myopic shift +/- SD of -5.63 +/- 1.33 diopters was observed after silicone oil removal (P < 0.0001). The absolute value of the refractive shift showed a strong correlation with the posterior radius of the IOL (r = 0.699, P < 0.0001).

CONCLUSION

IOL models with steeper posterior convex curvature result in larger refractive deviations in patients scheduled for silicone oil instillation.