Corneal shape changes after scleral buckling surgery

Higher Order Aberrations following Scleral Buckling Surgery in Patients with Rhegmatogenous Retinal Detachment

We aim to evaluate magnitudes of higher order aberrations (HOAs) from 3rd–6th order after scleral buckling (SB) for rhegmatogenous retinal detachment (RRD). A retrospective cross-sectional study of 19 patients with RRD who received SB (six receiving encircling SB, thirteen receiving segmental SB) was conducted. A wavefront analysis for surveying HOAs and other ophthalmic parameters were collected. Data between operated and fellow eyes, and a subgroup analysis of operated eyes, were analyzed by the Mann–Whitney U test, while a generalized linear model was applied to evaluate the correlation of HOAs to best-corrected visual acuity (BCVA) and optical symptoms. BCVA in the operated eyes was significantly worse (LogMAR: 0.18 ± 0.23 versus 0.05 ± 0.07, p = 0.001). Tilt (0.32 ± 0.14 versus 0.13 ± 0.08, p = 0.004), defocus (1.78 ± 0.47 versus 1.05 ± 0.17, p = 0.019) and coma (0.43 ± 0.11 versus 0.27 ± 0.09, p = 0.016) were significantly increased after SB. All root mean square (RMS), including RMS-3, RMS-4 and total RMS, were higher in operated eyes (all p < 0.05). Regarding Zernike terms, a significant elevation of vertical coma in the operated eyes was found (p = 0.038). In addition, tilt (0.41 ± 0.10 versus 0.17 ± 0.12, p = 0.007), defocus (2.27 ± 0.58 versus 0.82 ± 0.39, p = 0.001) and coma (0.59 ± 0.17 versus 0.11 ± 0.10, p = 0.015) were higher in the segmental subgroup, whereas spherical aberration (SA) was higher in the encircling subgroup (0.22 ± 0.04 versus 0.40 ± 0.15, p = 0.024) and RMS-4 and total RMS were increased in the segmental subgroup (both p < 0.05). Besides, tilt was correlated to worse BCVA (p = 0.036), whereas all four HOAs were correlated to the presence of optical symptoms (all p < 0.05). In conclusion, SB may increase HOAs, which could be associated with unfavorable postoperative visual outcomes and subject symptoms.

Incidence of Clinically Significant Aniseikonia Following Encircling Scleral Buckle Surgery: An Evaluation of Refractive and Axial Length Changes Requiring Intervention

To evaluate the incidence of symptomatic anisometropia and aniseikonia requiring intervention following surgery with combined pars plana vitrectomy (PPV) and broad 276 style encircling scleral buckle (ESB) for the repair of rhegmatogenous retinal detachments (RRD) and to report axial length (AL) and keratometry changes, a retrospective review of consecutive RRD patients treated with combined PPV and ESB between June 2016 until September 2019 was performed. All patients with symptomatic optically induced aniseikonia requiring additional interventions or surgical procedures including clear lens exchanges, secondary intraocular lens implants or contact lenses were documented. Keratometry and AL measurements were recorded for each eye and changes calculated. In total, 100 patients underwent combined PPV, ESB and endotamponade with mean age of 59.47 years (SD 11.49). AL was significantly increased (25.39 mm [SD 1.27] to 26.54 mm [SD 1.16], p = 0.0001), with a mean change of 1.15 mm (SD 0.67). Mean corneal astigmatism increased by –0.95 D (SD 0.51) in control eyes preoperatively and –1.33 (SD 0.87) postoperatively (p = 0.03). Over half of phakic patients (39/61; 64%) developed a visually significant cataract, subsequently undergoing surgery. Six of 100 patients developed symptomatic anisometropia with aniseikonia postoperatively (6%). Four proceeded with clear lens exchange despite absence of visually significant cataract (4%). Two of these initially trialled contact lenses (2%). One was intolerant, while the other decided to proceed with clear lens exchange for convenience. Only one patient (1%), being pseudophakic in both eyes, had persistent anisometropia/aniseikonia. AL and keratometry changes induced by encirclement with broad solid silicone rubber buckles are acceptable and similar to those reported previously using narrow encircling components, being unlikely to induce troublesome symptomatic anisometropia/aniseikonia. Many patients are phakic and develop visually significant cataracts, allowing correction of changes induced with the aim of visual restoration. A minority require more prolonged methods of visual rehabilitation, such as contact lens wear or clear lens exchanges. Caution and appropriate consent should be made in patients that are pseudophakic in both eyes at presentation.

Minimally interface vitrectomy for rhegmatogenous retinal detachment with a single break in young patients

Purpose

This study evaluates a new surgical technique consisting of minimal vitreous removal under air (minimal interface vitrectomy; MIV) to reduce postoperative complications while preserving the ability to address surgical factors at the retinal break.

Methods

This retrospective analysis examined the outcomes of minimal interface vitrectomies in consecutive cases, with a minimum 12-month follow-up period, of primary rhegmatogenous retinal detachment (RRD), recurrent RRD after pars plana vitrectomy (PPV), or failed surgery after primary scleral buckling surgery (SBS).

Results

Twelve eyes of 12 patients with RRD underwent MIV. The total surgical duration was 190–300 s (mean, 245.25 s). Eight (66.7%) eyes were treated with cryotherapy, and 4 (33.3%) with endolaser to seal the retinal break. Successful, complete retinal reattachment was achieved in all eyes and maintained during follow-up. No intra- or postoperative complications occurred and no patients developed inflammation or cataract during follow-up.

Conclusion and Importance

We effectively removed traction and subretinal fluid and treated breaks with endolaser or cryotherapy by using a novel minimal interface vitrectomy technique in this selected population.

The effect of scleral buckling on accommodative amplitude

Purpose

To evaluate the effect of scleral buckling on accommodative amplitude.

Design

Non-randomized, prospective, double masked clinical trial in which the fellow eye of patients undergoing scleral buckling served as a control.

Methods

Patients who underwent scleral bucking for the management of retinal detachment in at least one eye were enrolled. Accommodative amplitude was measured monocularly 1 month and 3 months post operatively by two masked optometrists using a near-point "push" technique and minus-to-blur technique. Accommodative amplitude in eyes that underwent scleral buckle surgery were compared to their fellow eyes. Buckle type, buckle location, lens status and age were analyzed. Generalized Estimation Equations (GEE) were used to compare means and percentages between two groups.

Results

Seventy-four eyes of 37 patients were included in the study. Median age was 44 years old (range: 31-67 years old) and 68.4% of patients were male (n = 24). Two patients required bilateral surgery. Thirty-six of 39 operated eyes (92.3%) were phakic and three were pseudophakic. In phakic eyes there was a significantly higher amplitude of accommodation in operated eyes compared to their fellow eyes at post-operative month one (0.99 diopters, p value = 0.002) and three (1.17 diopters, p value = 0.001). The difference in accommodative amplitude in post-operative eyes compared to control eyes did not reach statistical significance in pseudophakic eyes nor did it differ between those who had an encircling band and those with a segmental buckle at both one and 3 months after surgery (p value = 0.37 and 0.38, respectively). In those with a segmental buckle, inferior fixation resulted in a larger difference in accommodative amplitude compared to control eyes than any other location fixation. Age under 40 years old and better post-operative best corrected visual acuity (BCVA) both correlated with greater difference in accommodative amplitude compared to fellow eyes.

Conclusion

Compared to fellow eyes not undergoing surgery, those eyes that underwent scleral buckling had a greater accommodative amplitude with larger differences correlating with better post-operative BCVA and younger age.

Long-term Effect of Scleral Encircling on Axial Elongation

PURPOSE

To determine the long-term effect of scleral encircling on the progression of myopia.

DESIGN

Retrospective clinical cohort study.

METHODS

Setting: Single-center academic hospital (Severance Hospital).

STUDY POPULATION

The study included 76 eyes of 38 patients (mean age 37.21 ± 15.76) who had undergone retinal detachment surgery with scleral encircling. Observational Procedures: Axial length was measured preoperatively, at 6 months after surgery, and at the most recent visit. Patients were followed up for at least 12 months.

MAIN OUTCOME MEASURE

The changes of axial length per month between operated eyes and contralateral eyes (control group).

RESULTS

The operated group showed more rapid changes in axial length from 6 months after surgery to the time of the last follow-up than did the control group (0.020 ± 0.033 mm/month vs 0.002 ± 0.002 mm/month, P = .002; mean follow-up, 26.05 ± 11.39 months). Similar trends were observed during the entire follow-up period (0.065 ± 0.062 mm/month vs 0.008 ± 0.020 mm/month, P < .001). Subgroup analysis showed that both the myopic and highly myopic group showed no significant difference of change in rate of axial length during the first 6 postoperative months (P = .267), from 6 months after surgery to the final assessment point (P = .144), or over the entire observation period (P = .507).

CONCLUSIONS

Encircling the sclera may accelerate progression of myopia by significantly increasing axial length. The degree of myopia itself does not contribute to a significant difference in the increased axial length.

Flexible Optical Waveguides for Uniform Periscleral Cross-Linking

Purpose

Scleral cross-linking (SXL) with a photosensitizer and light is a potential strategy to mechanically reinforce the sclera and prevent progressive axial elongation responsible for severe myopia. Current approaches for light delivery to the sclera are cumbersome, do not provide uniform illumination, and only treat a limited area of sclera. To overcome these challenges, we developed flexible optical waveguides optimized for efficient, homogeneous light delivery.

Methods

Waveguides were fabricated from polydimethylsiloxane elastomer. Blue light (445 nm) is coupled into the waveguide with an input fiber. Light delivery efficiency from the waveguide to scleral tissue was measured and fit to a theoretical model. SXL was performed on fresh porcine eyes stained with 0.5% riboflavin, using irradiances of 0, 25, and 50 mW/cm² around the entire equator of the eye. Stiffness of scleral strips was characterized with tensiometry.

Results

Light delivery with a waveguide of tapered thickness (1.4–0.5 mm) enhanced the uniformity of light delivery, compared to a flat waveguide, achieving a coefficient of variation of less than 10%. At 8% strain, sclera cross-linked with the waveguides at 50 mW/cm² for 30 minutes had a Young's modulus of 10.7 ± 1.0 MPa, compared to 5.9 ± 0.5 MPa for no irradiation, with no difference in stiffness between proximally and distally treated halves. The stiffness of waveguide-irradiated samples did not differ from direct irradiation at the same irradiance.

Conclusions

We developed flexible waveguides for periscleral cross-linking. We demonstrated efficient and uniform stiffening of a 5-mm-wide equatorial band of scleral tissue.

Anatomical and Functional Results Following 23-Gauge Primary Pars Plana Vitrectomy for Rhegmatogenous Retinal Detachment: Superior versus Inferior Breaks

PURPOSE

In this retrospective study, we evaluated the anatomical and functional outcomes of patients with rhegmatogenous retinal detachment primarily treated with pars plana vitrectomy in regard to the location of the breaks. Methods. 160 eyes were enrolled in this study, divided into two groups based on break location: the superior break group (115 eyes) and the inferior break group (45 eyes). The main endpoint of our study was the anatomical success at 3 months following surgery.

RESULTS

Primary retinal reattachment was achieved in 96.5% of patients in group A and in 93.3% in group B (no statistically significant difference, OR 1.98, 95% CI: 0.4, 7.7). Mean BCVA change and intraoperative complication rate were also not statistically significantly different between the two groups (p > 0.05, OR: 1.0, 95% CI: 0.9, 1.01, resp.). Statistical analyses showed that macula status, age, and preoperative BCVA had a significant effect on mean BCVA change (p = 0.0001, p = 0.005, and p = 0.001, resp.).

CONCLUSION

This study supports that acceptable reattachment rates can be achieved using PPV for uncomplicated RRD irrespective of the breaks location and inferior breaks do not constitute an independent risk factor for worse anatomical or functional outcome.

Scleral buckling-induced ocular parameter changes in different age group patients of rhegmatogenous retinal detachment

PURPOSE

This study was aimed to evaluate the difference in the ocular parameter changes following scleral buckling (SB) for rhegmatogenous retinal detachment (RRD) in different age group patients.

MATERIALS AND METHODS

This prospective study included 26 eyes of 26 patients who underwent SB for uncomplicated RRD. The patients were divided into three age groups: 16-30 years (Group I), 31-45 years (Group II), and 46-60 years (Group III). Axial length (AL), anterior chamber depth (ACD), and corneal curvatures were measured preoperatively and postoperatively at 1 week, 1 month, and 3-month. The postoperative change and progression of these parameters were evaluated and compared between three age groups using nonparametric Wilcoxon signed-rank test and Kruskal-Wallis test.

RESULTS

At 3-month follow-up, a statistically significant postoperative AL increase, ACD decrease, and surgically induced astigmatism (SIA) were observed in all groups (Group I - 0.75 ± 0.32 mm, 0.21 ± 0.21 mm, and 1.5 ± 0.48 D, respectively; Group II - 0.79 ± 0.41 mm, 0.14 ± 0.04 mm, and 2.07 ± 1.18 D, respectively; Group III - 0.86 ± 0.33 mm, 0.16 ± 0.05 mm, and 1.56 ± 1.19 D, respectively). However, surgery-induced change for any parameter was not significantly different between the groups (P for AL [0.7955]; ACD [0.8805]; and SIA [0.5485]). Progression in postoperative changes in AL and ACD was insignificant during three follow-up examinations in all the groups. However, SIA of Group I continued to change significantly up to 3 months but stopped to change at 1 month only in Group II and III.

CONCLUSION

Age-related change in physical properties of ocular tissue does not have any major additional effect on the results of SB except that the postsurgical change in corneal curvature stops earlier in older patients compared to that in younger patients.

Changes in axial length, central cornea thickness, and anterior chamber depth after rhegmatogenous retinal detachment repair

BACKGROUND

This study was designed to measure changes in anterior chamber depth (ACD), central cornea thickness (CCT), and axial length (AL) after scleral buckle (SB) surgery or pars plana vitrectomy (PPV) for the repair of rhegmatogenous retinal detachment (RD).

METHODS

We prospectively reviewed the records of 245 eyes of 245 patients scheduled to undergo SB surgery and 238 eyes of 238 patients scheduled to undergo PPV. ACD, CCT, and AL were measured by spectral-domain optical coherence tomography (SD-OCT) and biometry, before surgery as well as 6 and 12 months postoperatively.

RESULTS

For both SB and PPV surgeries, ACD was observed to decrease significantly postoperatively, with this trend continuing throughout the follow-up period (p < 0.005). CCT showed no significant difference after PPV or SB surgery. AL increased significantly after SB surgery but not PPV.

CONCLUSION

Our results show that SB surgery altered the shape of the eye by changing both ACD and AL. PPV resulted in altered ACD. These findings should elucidate the changes to be expected after SB and PPV surgeries.

Short-term external buckling with pneumatic retinopexy for retinal detachment with inferior retinal breaks

PURPOSE

To introduce a new approach for short-term external scleral buckling with pneumatic retinopexy for the management of rhegmatogenous retinal detachment with inferior retinal breaks.

DESIGN

Retrospective, noncomparative, interventional case series.

METHODS

A review of 33 consecutive eyes of 31 patients who underwent external buckling with pneumatic retinopexy for uncomplicated rhegmatogenous retinal detachment with inferior retinal breaks from December 2006 through December 2010. An external buckle was made of a 505 sponge sutured along the blunt side of a 279 tyre (MIRA Inc). The buckle was inserted deeply into the inferior fornix without suture after pneumatic retinopexy and was kept in place for 3 days. Primary and final anatomic outcomes, visual acuity, and adverse events were recorded.

RESULTS

All patients tolerated the procedure. The mean follow-up period was 24.0 months (range, 9 to 61 months). Primary success, defined as successful retinal reattachment within 6 months without further treatment, was achieved in 29 (87.9%) eyes. All patients attained final retinal reattachment (100%). Overall, the mean best-corrected visual acuity improved significantly at the end of follow-up (0.30 logarithm of the minimal angle of resolution units; Snellen equivalent, 6/12), compared with the preoperative best-corrected visual acuity (0.82 logarithm of the minimal angle of resolution units; Snellen equivalent, 6/38; P < .001).

CONCLUSIONS

Short-term external buckling with pneumatic retinopexy is a novel and effective treatment for rhegmatogenous retinal detachment with inferior retinal breaks, with a comparable success rate with other treatment methods. This approach also can avoid complications of long-term buckle implantation. Further comparative cohort studies may be necessary to compare the clinical efficacy with other conventional operations.

Non-buckled vitrectomy for retinal detachment with inferior breaks and proliferative vitreoretinophathy

AIM

To investigate the efficacy of non-buckled vitrectomy with classical endotamponade agents in the treatment of primary retinal detachment (RD) complicated by inferior breaks and proliferative vitreoretinophathy (PVR).

METHODS

A retrospective, consecutive and case series study of 40 patients with inferior break RD and PVR ≥C1 was conducted. All patients underwent a standard 3-port 20-gauge pars plana vitrectomy (PPV) with gas or silicone oil tamponade without supplementary scleral buckling. The vitreous and all proliferative membrane were completely removed, and retinectomy was performed when necessary. The mean follow-up was 12.5 months. The primary and final anatomic success rate, visual acuity and complications were recorded and analyzed.

RESULTS

Primary anatomic success rate was achieved in 35 of 40 eyes (87.5%) and the final anatomic success rate was 100%. The most common cause of redetachment was recurrent PVR. The best-corrected visual acuity (BCVA) at final follow-up was improved in 34 eyes (85%), remained stable in 1 eye (2.5%), and worsened in 5 eyes (12.5%). The mean visual acuity at final follow-up was improved significantly (P=0.000).

CONCLUSION

This retrospective study provides evidence that vitrectomy without scleral buckling seemed to be an effective treatment for inferior break RD with PVR. With complete removal of vitreous and proliferative membranes and timing of retinectomy, the inferior breaks which complicated with PVR could be closed successfully without additional scleral buckling.

[Effects of encircling scleral buckling on the morphology and biomechanical properties of the cornea]

OBJECTIVE

To investigate the effects of encircling scleral buckle (SB) on corneal biomechanical properties of the cornea and its morphological parameters.

METHODS

We prospectively examined twelve eyes diagnosed with vitreous haemorrhage undergoing pars plana vitrectomy (PPV), and fifteen eyes undergoing combined PPV and scleral buckle (PPV/SB) for repair of rhegmatogenous retinal detachment (RRD). Corneal biomechanical properties, including corneal hysteresis (CH) and corneal resistance factor (CRF), were measured with an Ocular Response Analyser (ORA) before and 1-month postoperatively. The ORA also determined the values of intraocular pressure (IOPg) and corneal compensated IOP (IOPcc). Finally, four morphological parameters of the cornea were measured with the Orbscan II topographer (Orbtek, Inc.): mean corneal power, thinnest corneal point (μm), and anterior chamber depth (ACD).

RESULTS

CH decreased significantly from 10.2+/-1.7mmHg to 7.6+/-1.1mmHg after PPV/SB (p=0.003), but not after PPV alone (9.8+/-3.2mmHg vs 11.6+/-2.7mmHg, P=.465). CRF did not change significantly after surgery in both groups. IOPg and IOPcc increased significantly in the PPV/SB group (P=.019 and P=.010, respectively) but not in PPV group (P=.715 and P=.273, respectively). Unlike the PPV group, values were significantly higher than IOPg values before (P=.001) and after surgery (P=.003) in the PPV/SB group IOPcc. Neither the PPV/SB group nor the PPV group showed any significant changes in the corneal morphological parameters after surgery (P>.05).

CONCLUSIONS

SB surgery leads to a change in the corneal biomechanical properties without altering corneal morphological parameters. It may cause an underestimation error in IOP measurement. PPV may be a less invasive surgical approach for the repair of noncomplex RRD than PPV/SB.

Retinal complications of phakic intraocular lenses

High myopia has always been a challenge for refractive correction. Current laser surgical techniques, however, fall short of correcting high refractive errors due to lack of predictability, regression, corneal ectasia, and introduction of high order optical aberration. Phakic intraocular lenses (IOL) have been proposed as an effective refractive surgical procedure for the correction of severe myopia, but, despite recent advances in implant material technology and design, their concept is still under clinical investigation. Most of the concern regarding the complications of phakic IOLs focuses on the anterior segment of the eye. This review examines the posterior segment complications associated with phakic IOL implantation, evaluates possible pathogenetic mechanisms and discusses posterior segment complications, prevention and management.

A review of astigmatism and its possible genesis

Astigmatism is a refractive condition encountered commonly in clinical practice. This review presents an overview of research that has been carried out examining various aspects of this refractive error. We examine the components of astigmatism and the research into the prevalence and natural course of astigmatic refractive errors throughout life. The prevalence of astigmatism in various ethnic groups and diseases and syndromes is also discussed. We highlight the extensive investigations that have been conducted into the possible aetiology of astigmatism, however, no single model or theory of the development of astigmatism has been proven conclusively. Theories of the development of astigmatism based on genetics, extraocular muscle tension, visual feedback and eyelid pressure are considered. Observations and evidence from the literature supporting and contradicting these hypotheses are presented. Recent advances in technology such as wavefront sensors and videokeratoscopes have led to an increased understanding of ocular astigmatism and with continued improvements in technology, our knowledge of astigmatism and its genesis should continue to grow.

Ocular surface influences on corneal topography

The shape of a cornea, as measured by corneal topography, can be influenced by a variety of factors. Direct and obvious influences on corneal shape include corneal pathology, corneal surgery, and contact lenses. With the modern and widespread use of computerized videokeratoscopy, subtle topographic changes from other external and systemic influences can now be detailed. The purpose of this review is to examine ocular surface influences and indirect surgical, pathological, and pharmacological factors that affect the corneal shape and acquired topographic maps. The clinical consequences of altered corneal topography will be highlighted throughout.

Corneal ectasia after scleral buckling surgery

PURPOSE

To describe a case of corneal ectasia with marked asymmetric progression attributable to encircling buckle surgery for retinal detachment.

METHODS

Case report.

RESULTS

A 72-year-old man developed clinical signs of pellucid marginal degeneration in 1 eye after placement of an encircling scleral buckle. The fellow eye showed normal slit-lamp examination, with topographic signs of forme-fruste pellucid marginal degeneration.

CONCLUSION

Patients with forme-fruste pellucid marginal degeneration may show progression and clinical manifestations after encircling scleral buckle, probably by changes in ocular physiology and corneal biomechanics.

Corneal topographic changes after scleral buckling

PURPOSE

To evaluate corneal topographic changes and induced corneal astigmatism after scleral buckling (SB).

METHODS

This interventional case series includes all patients who had undergone scleral buckling for rhegmatogenous retinal detachment (RRD) during a 1-year period. Patients were divided into four groups according to type and extent of scleral buckling which depended on the discretion of a retina specialist. Videokeratography was performed for all patients preoperatively and repeated 1 and 3 months after SB.

RESULTS

Thirty-nine eyes of 39 patients (29 male, 74.7%) with mean age of 50.35+/-20 years (range 13-80) were finally analyzed. There was no statistically significant difference among the groups in terms of preoperative corneal astigmatism, surface regularity index (SRI), surface asymmetry index (SAI), mean keratometry (mean K), and potential visual acuity (PVA ). Overall, preoperative mean K was 43.97+/-1.78 D, which reached 44.2+/-2.02 D and 43.92+/-2.16 D 1 and 3 months after the operation. Mean preoperative SRI was 0.58+/-0.4, which increased to 1.24+/-1.18 and 1.29+/-1.13 1 and 3 months after the operation respectively. Mean preoperative SAI was 0.39+/-0.21, which increased to 0.73+/-0.37 and 0.75+/-0.66 1 and 3 months after the procedure. Changes in SAI at 1 and 3 months following SB were significant (p values <0.001); however, these postoperative values were not significantly different. Mean preoperative PVA was 0.07+/-0.75 logMAR (equivalent to 20/20) but decreased to 0.24+/-0.25 (equivalent to 20/30) and 0.27+/-0.29 (equivalent to 20/40) 1 and 3 months after SB, respectively.

CONCLUSIONS

Significant changes in corneal topographic indices including increases in SRI and SAI and a concomitant decrease in PVA may occur after SB procedures. These induced changes must be considered and appropriately addressed postoperatively to provide the best possible corrected vision.

Surgically-induced Corneal Changes Following Macular Translocation with Punctate Retinotomies and Chorioscleral Infolding (Limited Macular Translocation)

Introduction: To report the sequential changes in corneal topography and astigmatism following limited macular translocation. Clinical Picture and Treatment: A 45-year-old-man who underwent limited macular translocation for idiopathic subfoveal choroidal neovascularisation in the right eye was evaluated by corneal topography and manifest refraction preoperatively and serially for 1 year postoperatively. Outcome: An increase in astigmatism with corneal steepening along meridians corresponding to the area of chorioscleral infolding was observed and this persisted for 1 year after surgery. Vector-analysed astigmatic change showed significant surgically induced astigmatism of 2.18 dioptres (D) X 52.9 degrees, 2.17 D X 57.8 degrees and 2.56 D X 59.1 degrees at 2, 5 and 12 months after surgery respectively. Conclusion: Surgically induced corneal changes are evident after limited macular translocation and may remain up to 1 year after surgery. Key words: Astigmatism, Choroidal neovascularisation, Corneal topography, Ophthalmologic surgical procedure

The Effect of Scleral Buckling Surgery on Corneal Astigmatism, Corneal Thickness, and Anterior Chamber Depth

PURPOSE

To evaluate the effect of scleral buckling surgery on corneal topography, corneal thickness, and anterior chamber depth.

METHODS

Thirty-two eyes of 32 patients who underwent encircling buckling surgery for rhegmatogenous retinal detachment were included in the study. Fellow eyes comprised the control group. Orbscan II topography system was used to determine the changes in corneal topography, corneal thickness, and anterior chamber depth before surgery and 1 week, 1 month, and 3 months after surgery. Statistical analyses used in the study were independent t test, paired t test, one way analysis of variance, and correlation analyses.

RESULTS

Postoperatively, mean central corneal astigmatism at 1 week, 1 month, and 3 months was 4.3 +/- 2.0 diopters (D), 3.3 +/- 1.6 D, and 3.1 +/- 1.0 D, respectively. The change between 1 week and 3 months was statistically significant. Central cornea was thickened at the first postoperative week. The thickness gradually decreased to the preoperative levels at 3 months. Anterior chamber depth decreased, and the anterior chamber remained shallow after the surgery. The comparison between preoperative (2.94 +/- 0.6 mm) and postoperative anterior chamber depth was statistically significant at 1 week (2.57 +/- 0.7 mm), 1 month (2.83 +/- 0.7 mm), and 3 months (2.73 +/- 0.6 mm).

CONCLUSIONS

Corneal changes after scleral buckling surgery were mild to moderate and the cornea almost resumed its preoperative parameters in 3 months' time. However, the anterior chamber remained shallow during 3 months of follow-up.

Laser in situ Keratomileusis for Correction of Myopia in Eyes After Retinal Detachment Surgery

PURPOSE

To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) for correction of myopia in eyes with previous retinal detachment surgery.

METHODS

A retrospective review was conducted of all consecutive eyes that underwent LASIK after retinal detachment surgery. Data was collected regarding previous ocular surgery and its time prior to LASIK, intra- and postoperative complications, and visual outcome measures pre- and postoperatively.

RESULTS

Ten eyes with previous retinal detachment surgery were scheduled for LASIK. One eye was excluded from data analysis as LASIK was aborted due to inadequate microkeratome suction because of conjunctival scarring. Nine eyes underwent an uneventful LASIK procedure. On average, LASIK was performed 130+/-123 months following retinal detachment surgery. Postoperative LASIK follow-up was 14.8+/-12.5 months. No significant intraoperative, postoperative, or retinal complications were observed. The mean preoperative spherical equivalent refraction was -9.00+/-3.00 diopters (D), uncorrected visual acuity (UCVA) was 0.06+/-0.02, and best spectacle-corrected visual acuity (BSCVA) was 0.64+/-0.16. At the end of follow-up, the mean spherical equivalent refraction was 0.65+/-0.88 D, mean UCVA was 0.57+/-0.14, and mean BSCVA was 0.72+/-0.19. Differences between BSCVA before and after LASIK were statistically significant (P=.038). At final follow-up, the safety index was 1.22 and efficacy index was 1.01.

CONCLUSIONS

Laser in situ keratomileusis was found to be a safe and efficient option for treating refractive errors in eyes with previous retinal detachment surgery.

Vitrectomy and gas for inferior break retinal detachments: are the results comparable to vitrectomy, gas, and scleral buckle?

AIMS

To compare the success rates of vitrectomy and gas with vitrectomy, gas, and buckle in the treatment of inferior break retinal detachments.

METHODS

A retrospective case note review of 86 patients who presented with inferior break retinal detachments was carried out. An inferior break was defined as a horseshoe tear present between 4 and 8 o'clock. Patients were analysed in two groups; group A consisted of 41 patients who underwent a vitrectomy and gas, group B consisted of 45 patients who underwent a vitrectomy, gas, and scleral buckle. The features of the retinal detachment, peroperative and postoperative complications, and outcomes of treatment were recorded for each patient.

RESULTS

The primary anatomical success rate at 3 months was 89% in group A versus 73% in group B (p = 0.11). There was no statistical difference in the complication rate between the two groups (p = 0.819). The most common cause of treatment failure was proliferative vitreoretinopathy, 20% (n = 9) in group B compared with 5% (n = 2) in group A and this reached statistical significance (p = 0.0159). There was a higher rate of epiretinal membrane development in group B (p = 0.0004). The final attachment rate was not statistically different between the two groups, 95% (39) in group A and 93% (42) in group B (p = 1.0).

CONCLUSION

Vitrectomy and gas without the application of a scleral buckle may be used to safely treat inferior break retinal detachments. It may be used as an alternative to vitrectomy, gas, and buckle which has an increased risk of choroidal haemorrhage, requires a longer operating time, and has all the associated complications of a scleral buckle.

Corneal topographic changes following retinal surgery

Background

To study the effect of retinal/ vitreoretinal surgeries on corneal elevations.

Methods

Patients who underwent retinal/ vitreoretinal surgeries were divided into 3 groups. Scleral buckling was performed in 11 eyes (Group 1). In 8 (25%) eyes, vitreoretinal surgery was performed along with scleral buckling (Group 2). In 12 eyes, pars plana vitrectomy was performed for vitreous hemorrhage (Group 3). An encircling element was used in all the eyes. The parameters evaluated were best-corrected visual acuity (BCVA), change in axial length, and corneal topographic changes on Orbscan topography system II, preoperative and at 12 weeks following surgery.

Results

There was a statistically significant increase in anterior corneal elevation in all the three groups after surgery (p = 0.003, p = 0.008 & p = 0.003 respectively). The increase in posterior corneal elevation was highly significant in all the three groups after surgery (p = 0.0000, p = 0.0001 & p = 0.0001 respectively). The increase in the posterior corneal elevation was more than the increase in the anterior elevation and was significant statistically in all the three groups (group I: p = 0.02; group II: p = 0.01; group III: p = 0.008).

Conclusions

Retinal/ vitreoretinal surgeries cause a significant increase in the corneal elevations and have a greater effect on the posterior corneal surface.

Laser in situ keratomileusis as treatment for anisometropia after scleral buckling surgery

Scleral buckling is an excellent procedure for retinal reattachment but can induce disabling refractive errors. Laser in situ keratomileusis (LASIK) has been proven effective for the reduction of refractive errors induced by ophthalmic surgery. We describe the case of a 53-year-old man who developed symptomatic anisometropia after placement of a scleral buckle for repair of a rhegmatogenous retinal detachment (RD). After the scleral buckling procedure, he retained excellent best corrected visual acuity but could not tolerate spectacle or contact lens correction. Thirty-four months after the scleral buckling procedure, LASIK was performed to correct myopic astigmatism with excellent refractive and functional results. This case demonstrates that LASIK may be safe and effective for the correction of refractive errors induced by RD repair.

Corneal topographic changes after retinal detachment surgery

PURPOSE

To evaluate the changes in corneal topography after scleral buckling surgery for retinal detachment.

METHODS

Twenty-one eyes of 21 patients with the diagnosis of retinal detachment were included in this prospective study. Scleral buckling surgery was performed on all patients. The corneal topography of each was measured before surgery and at 1 week and 1 and 6 months after surgery by computer-assisted videokeratoscopy using the EyeSys 2000 Corneal Analysis System. Changes in corneal videokeratographies were analyzed using the Holladay Diagnostic Summary (HDS) software package.

RESULTS

A statistically significant central corneal steepening (average, 1.8 diopter) was noted 1 week after surgery. The total and irregular astigmatic components both revealed a significant but transient increase in the first postoperative month. All these topographic changes persisted for as long as 6 months but returned to preoperative values afterward.

CONCLUSION

Scleral buckling was found to induce transient changes in corneal topography producing both myopia and corneal astigmatism. Videokeratography is helpful for documenting such corneal changes after scleral buckling surgery for retinal detachment.

Corneal shape change during accommodation

PURPOSE

To investigate whether accommodation induces any changes in central corneal curvature.

METHODS

Shape changes were measured on 14 subjects using a keratometer modified to enable a change in focus to occur without a change in vergence. All subjects were emmetropic and their ages ranged from approximately 20 to 28 years.

RESULTS

In 11 of the 14 subjects a difference in central corneal curvature, of around 0.4 D in at least one principal meridian, was found when focus was changed between distant and near targets. In 9 subjects the curvature was greater for near focus in at least one meridian. In 5 subjects the change in one meridian was opposite in effect to what would be expected, i.e. the curvature was greater at distance than at near.

CONCLUSION

The study suggests that accommodation may have some effect on corneal shape.

Relationships between vitreoretinal and refractive surgery

OBJECTIVE

To describe retinal complications after posterior chamber phakic intraocular lens (PCPIOL) implantation and refractive surgery complications after scleral buckling surgery.

DESIGN

Retrospective, noncomparative, small case series.

PARTICIPANTS

Four patients in whom retinal detachment developed after PCPIOL implantation and two patients with previously placed encircling scleral buckles in whom corneal steepening developed after laser in situ keratomileusis (LASIK).

INTERVENTION

The four patients with retinal detachment after PCPIOL implantation underwent vitreoretinal surgery. One of the two patients in whom corneal steepening developed after LASIK underwent buckle removal.

MAIN OUTCOME MEASURES

The main parameters evaluated were vitreoretinal findings, corneal topography, and pachymetry.

RESULTS

Retinal attachment was achieved for all patients. Mean postoperative best-corrected visual acuity (BCVA) was 20/30. One patient lost one line of BCVA. One patient with corneal steepening achieved partial corneal flattening after buckle removal.

CONCLUSIONS

Vitreous base stimulation related to PCPIOL implantation and manipulation during LASIK may trigger retinal complications. Laser in situ keratomileusis in patients with previously placed scleral buckles may result in unexpected corneal steepening.

Induced corneal astigmatism after macular translocation surgery with scleral infolding

OBJECTIVE

To document the corneal astigmatism that occurs with macular translocation after scleral infolding surgery.

DESIGN

Retrospective case series of a nonrandomized clinical trial.

PARTICIPANTS

Eight consecutive age-related macular degeneration patients (eight eyes) with choroidal neovascularization who underwent macular translocation with scleral infolding at the Duke University Eye Center from December 1998 through October 1999.

METHODS

We retrospectively reviewed the charts of eight consecutive patients who underwent macular translocation surgery involving scleral infolding in the superotemporal quadrant. Two patients subsequently underwent release of scleral infolding.

MAIN OUTCOME MEASURES

After surgery, these eyes were evaluated for corneal astigmatism with manifest refraction, keratometry, and computerized corneal topography.

RESULTS

All eight eyes of eight patients revealed marked degrees of corneal astigmatism. Measurement of astigmatism via manifest refraction, keratometry, and corneal topography confirmed postoperative astigmatism corresponding to the axis of the scleral infolding. The amount of corneal astigmatism ranged from 1.75 to 7.37 diopters (D; mean, 4.60 D), with steepening along the axis of scleral infolding in the superotemporal quadrant of each eye (mean, 42.50 degrees from vertical; range, 24 degrees -66 degrees from vertical). Release of scleral infolding in two patients resulted in significant reduction of corneal astigmatism.

CONCLUSIONS

Scleral shortening procedures used in macular translocation surgery may induce large amounts of corneal astigmatism. These patients should be assessed with keratometry and corneal topography to determine the accurate amount and axis. Thereafter, contact lens fitting or scleral infolding release may be considered as therapeutic options for large amounts of astigmatism persisting after surgery.

Corneal surface changes after pars plana vitrectomy and scleral buckling surgery

PURPOSE

To evaluate the changes in corneal shape after pars plana vitrectomy, encircling buckling surgery, and a combination of the 2 procedures.

SETTING

Assaf Harofeh Medical Center, Zrifin, and Goldshlager Eye Institute, Tel Hashomer, Israel.

METHODS

In a prospective clinical study, 61 eyes of 61 patients were assigned to 1 of 3 groups based on the type of procedure: pars plana vitrectomy, encircling buckle and pars plana vitrectomy, or encircling buckle. The eyes had corneal keratometry (TMS-1), visual acuity measurement, and videokeratography (TMS-1) preoperatively and 2 days, 1 week, and 1 and 3 months postoperatively. The topographic parameters statistically analyzed were the corneal surface cylinder, simulated keratometry, surface regularity index, surface asymmetry index, standard deviation of corneal power, average corneal power, and irregular astigmatism index.

RESULTS

The measurements of all topographic indices were statistically significantly different from baseline measures 2 and 7 days postoperatively in all 3 groups. However, at 1 and 3 months, there was no significant difference from preoperatively in any index. Postoperative best corrected visual acuity was statistically significantly different from preoperatively.

CONCLUSIONS

All corneal surface indices were significantly altered after all 3 types of surgery. Corneal surface measurements returned to preoperative values by 1 month postoperatively and remained stable until the final follow-up at 3 months.

Efficacy of removal of buckle after scleral buckling surgery for retinopathy of prematurity

BACKGROUND OR PURPOSE: A series of encouraging reports over the past decade indicate that scleral buckling (SB) surgery may lessen or eliminate vitreoretinal traction in advanced retinopathy of prematurity (ROP). The effects of SB surgery on refraction and ocular growth, however, have not been demonstrated. We investigated the effects of postoperative removal of buckle in infants whose retinas were reattached in stage 4 ROP.

METHODS

Selected for study were 6 eyes of 3 patients whose retinas had been reattached by placing an encircling buckle, 2.5 mm in width, around the eye and whose buckles were subsequently removed. Axial lengths and refractive errors were compared before and after removal of the buckles. The patients were examined for at least 3 years after removal.

RESULTS

There was high myopia in all eyes treated for stage 4 ROP with SB. All retinas remained attached after removal of the buckle. Although there was a variable degree of increase in axial length, myopic refractive error tended to decrease after removal of the buckle.

CONCLUSIONS

There was some decrease in degree of myopia without resulting in retinal detachment or continued vitreous traction after buckle removal following SB surgery for ROP.

Changes in axial length after retinal detachment surgery

PURPOSE

To evaluate changes in axial length and corneal curvature after an encircling procedure combined with segmental buckling.

MATERIALS AND METHODS

We prospectively analysed cases with rhegmatogenous retinal detachment treated with an encircling band and scleral buckling surgery, comparing the pre-and postoperative ultrasonographic measurements of axial length and corneal curvature, and patients' age and sex in relation to the axial length of the eyeballs. We studied 74 patients (25 female, 49 male, aged 14-78 years, mean 46.7 years), who underwent retinal detachment surgery in 1995 and 1996.

RESULTS

Axial eye length was significantly increased by surgery (median 0.77 mm one month after surgery). One year after treatment the elongation of the eye had decreased by 0.20 mm. The average increase of corneal curvature was 0.22 D one month after surgery, and 0.43 D at one year. The distribution of axial length showed a significant preponderance of eyes with a longer axial length among males.

CONCLUSIONS

Encircling with a scleral buckling procedure with moderate indentation causes axial elongation of the eye.