Refractive Changes Induced by Strabismus Corrective Surgery in Adults

Corneal tomography changes following major (6 mm) medial rectus muscle recession: a prospective cohort study using Pentacam®

INTRODUCTION

The aim of this study is to evaluate changes in corneal astigmatism, axial anterior corneal curvature, as well as changes in the anterior chamber depth and central corneal thickness, 2 months following the unilateral recession of medial rectus muscle in children.

METHODS

Thirty-three children with esotropia were prospectively evaluated following unilateral medial rectus muscle recession, using Pentacam®. Comparisons were made between the operated and fellow unoperated eyes, pre, and postoperatively. The assessment was made for changes in the radius of axial curvature on major meridians at 3 and 3.5 mm from the optical corneal center in the mid-peripheral zone. Astigmatism changes of the anterior and posterior corneal surface were calculated using vector analysis software (astigMATIC®). ANOVA model was used to examine the interaction between age or central corneal thickness and postoperative changes in anterior and posterior surface corneal astigmatism.

RESULTS

In the intervention group, changes in anterior and posterior corneal surface astigmatism were statistically significant, with a mean increase of 0.59Dx92 and 0.08Dx91, respectively. In the mid-peripheral corneal zone, there is an increase in the radius of anterior corneal axial curvature more evident nasally 3.5 mm from the corneal center on the horizontal meridian, with corresponding decrease superiorly and inferiorly at 3 and 3.5 mm from the corneal center on the vertical meridian.

DISCUSSION

The changes in total astigmatism of the operated eyes are mainly attributed to the anterior corneal surface. These changes are associated with flattening in the 180 meridian of the cornea, leading to a shift to "with-the-rule" astigmatism.

Şaşılık Cerrahisinin Refraksiyon Kusuru ve Ön Segment Ölçümleri Üzerine Etkisi

Aim: This study aimed to investigate the effects of horizontal strabismus surgery on refractive error and anterior segment parameters. Material and Methods: Fifty-four eyes of 27 patients were included in this study. Patients underwent repeated refraction measurements and anterior segment evaluation preoperatively, first week, first month, third month, and sixth month postoperatively. Patients were divided into three groups, those who underwent resection (group 1), recession (group 2), and healthy eyes without any surgical intervention (group 3). Results: The mean age of the patients was 24.4±11.1 years and 14 (51.9%) were female. There was a statistically significant difference in central corneal thickness in group 2 before and after surgery (p=0.037). The mean central corneal thickness was highest in the first week with 548.14±40.42 µm and lowest in the first month with 541.50±41.75 µm after surgery. There was a statistically significant difference in cell density (p=0.004) and mean cell area (p=0.004) between groups 1 and 2 in the first week after surgery. The cell density level was statistically significantly higher in group 1 in all postoperative measurements. In addition, the mean cell area level was statistically significantly lower in group 1. Conclusion: Strabismus surgery has an effect on anterior segment parameters in addition to correcting eye movements and visual axis. Depending on the type of intervention, the number of affected anterior segment parameters also varies. In the management of the patient in the postoperative period, the anterior segment structures should be carefully evaluated at each examination and the findings should be noted.

Corneal Astigmatic and Refractive Changes after Rectus Muscle Surgery

Objective:In the present study, we investigated the postoperative astigmatic and refractive changes in patients with rectus muscle strabismus surgery. Materials and methods:Ninety-three eyes of 51 patients who underwent strabismus surgery at Amir- Almomenin Hospital, Rasht, Iran, were enrolled. The ocular measurements before surgery as well as one month, three and six months postoperatively included cycloplegic refraction, the degree of near and far deviation, mean corneal power, mean keratometry, spherical equivalent (SE) and the change of astigmatism cylinder (measured using power vector analysis). All data were analyzed using SPSS software, version 21. Results:The mean age of participants was 18.31±14.58 years. A similar myopic shift was observed in all deviation groups. The mean SE values differed according to the type of surgery one month and three months postoperatively, with maximum change being seen in medial rectus (MR) recess + inferior oblique (IO) myectomy and in MR recess and lateral rectus (LR) recess six months after surgery. The change in mean J0 remained significant six months postoperatively only in MR recess surgery and in medial and lateral rectus recess groups based on topography (both P<0.001). The postoperative J0 and J45 differed according to the type of surgery (PP<0.001 and 0.007, respectively). The mean keratometry was different before-after LR recess (the minimum change), MR recess and MR recess + IO myectomy groups (the maximum change; PP<0.05). Conclusion:Refractive error toward myopic shift and with-the-rule (WTR) astigmatism are common after strabismus surgery on the rectus muscles, most of which sustain until six months postoperatively.

Long-term astigmatism changes following horizontal muscle recession: a prospective cohort study

Strabismus surgery may cause refractive changes, particularly in astigmatism. The aim of this study is to evaluate those changes in astigmatism two and 12 months following unilateral recession of horizontal rectus muscles in children. The authors prospectively evaluated 66 children with esotropia or exotropia, that would undergo a unilateral recession strabismus surgery. Comparisons were made between the 66 eyes that would undergo strabismus surgery and the fellow unoperated 66 eyes of the same children. The 66 eyes that would undergo strabismus surgery were divided into medial (38 eyes) and lateral (28 eyes) rectus muscle subgroups, and further, into subgroups based on the astigmatism axis preoperatively (with-the-rule astigmatism: 35 eyes, no astigmatism: 20 eyes, oblique astigmatism: 10 eyes, against-the-rule astigmatism: 1 eye). All patients were examined one day preoperatively, and then, two and 12 months postoperatively. Paired tests were conducted, and the significant level was set to 0.05 or was adjusted for subgroups. Mean age of children included was 6.73 years (SD = 3.19). Mean astigmatism values preoperatively, 2 and 12 months postoperatively were 0.92D (SD = 0.95), 1.45D (SD = 1.04) and 1.50D (SD = 1.10), respectively, for the eyes that underwent strabismus surgery. A statistically significant mean increase of 0.58D in astigmatism values in the eyes that underwent strabismus surgery was observed 12 months postoperatively (p < .005). Astigmatism values in the eyes that did not undergo strabismus surgery did not statistically significantly change during the observation period. The increase of the absolute values of astigmatism in medial and lateral rectus muscle subgroups was similar, 0.59D (SD = 0.10) and 0.57D (SD = 0.11), respectively. For the eyes that had with-the-rule astigmatism and no astigmatism preoperatively, a statistically significant increase was shown 12 months postoperatively (0.64D and 0.66D respectively) (p < .005). Changes in astigmatism were observed in the eyes which underwent recession of horizontal rectus muscles compared to the fellow eyes, which did not undergo any intervention. An increase in cylindrical power was noted in the eyes that had with-the-rule and no astigmatism prior to surgery. This increase may be interpreted by the decreased tension of the recessed rectus muscle following strabismus surgery. Decreased forces, caused by the recessed horizontal rectus muscle, acting on the sclera on 180-degree meridian may lead to corneal flattening on this particular meridian and consequently, a corneal steepening on the 90-degree meridian. These changes seem to be stable during the first 12 postoperative months.

Changes in astigmatism after horizontal muscle recession strabismus surgery: A retrospective cohort study

Purpose:

The aim of this study was to evaluate the changes in astigmatism after unilateral recession of horizontal rectus muscles in pediatric patients.

Methods:

The authors retrospectively evaluated the medical history of 52 children with esotropia or exotropia, that underwent a unilateral recession strabismus surgery. The intervention group consisted of the 52 eyes that underwent strabismus surgery, and the control group consisted of the other 52 fellow unoperated eyes of the same participants. The intervention group was divided into medial and lateral rectus muscle subgroups, and four subgroups based on the astigmatism axis preoperatively (A: with-the-rule astigmatism, B: no astigmatism, C: intermediate meridians, D: against-the-rule astigmatism). All patients were examined one day preoperatively, and then, six weeks postoperatively. Paired tests were conducted, and the significant level was set to 0.05 or was adjusted for subgroups.

Results:

A mean difference 0.43 D of astigmatism (95% CI: 0.27, 0.59) was observed after the surgery between intervention and control group (P < 0.001). Astigmatism change (postoperative - preoperative) in subgroup A was 0.50 D (P < 0.001) and in subgroup B was 0.75 D (P < 0.001). Moreover, astigmatism changes of 0.50 D were found in both lateral (P < 0.001) and medial rectus muscle group (P = 0.002).

Conclusion:

Strabismus surgery appears to be associated with alterations in astigmatism, and in particular increase in cylindrical power in the eyes that had with-the-rule astigmatism or no astigmatism preoperatively. Those changes should be considered when planning the operation, to avoid transforming clinically non-significant astigmatism into clinically significant.

Identification of rare paired box 3 variant in strabismus by whole exome sequencing

AIM

To identify the potentially pathogenic gene variants that contributes to the etiology of strabismus.

METHODS

A Chinese pedigree with strabismus was collected and the exomes of two affected individuals were sequenced using the next-generation sequencing technology. The resulting variants from exome sequencing were filtered by subsequent bioinformatics methods and the candidate mutation was verified as heterozygous in the affected proposita and her mother by sanger sequencing.

RESULTS

Whole exome sequencing and filtering identified a nonsynonymous mutation c.434G-T transition in paired box 3 (PAX3) in the two affected individuals, which were predicted to be deleterious by more than 4 bioinformatics programs. This altered amino acid residue was located in the conserved PAX domain of PAX3. This gene encodes a member of the PAX family of transcription factors, which play critical roles during fetal development. Mutations in PAX3 were associated with Waardenburg syndrome with strabismus.

CONCLUSION

Our results report that the c.434G-T mutation (p.R145L) in PAX3 may contribute to strabismus, expanding our understanding of the causally relevant genes for this disorder.