Effect of strabismus surgery on ocular axial length, anterior chamber depth, and intraocular pressure

Investigation of the effects of single and two-muscle horizontal rectus surgeries on macular microvasculature

PURPOSE

To investigate the changes in posterior segment hemodynamics caused by horizontal rectus muscle surgeries using the optic coherence tomography angiography (OCTA).

METHODS

Patients who underwent at least one horizontal rectus recession, resection, or combination surgery were included. The patients were evaluated with an OCTA preoperatively and 30 days postoperatively. Postoperative changes in superficial capillary plexus (SCP)-vessel density (VD), deep capillary plexus (DCP)-VD, foveal avascular zone (FAZ) area and choriocapillaris (CC)-flow area parameters were examined. The mean differences (Δ) for the parameters in which significant changes were detected in the whole operated eyes group were compared between the single- and two-muscle surgery groups.

RESULTS

Twenty-five eyes of 24 patients with an average age of 16.40 ± 6.75 years (5-29) were included. Of the eyes, 10 underwent single muscle recession surgery. Two-muscle surgeries were performed in 15 eyes. SCP-VD in the superior parafoveal region increased significantly postoperatively (53.23 ± 4.11% vs. 54.54 ± 3.67%, p = 0.032). For DCP-VD, there was a statistically significant increase in all zones, except the superior hemisphere and fovea regions (p < 0.05 for all). FAZ area did not change significantly (p = 0.207). There was a significant increase in the CC-flow area (2.171 ± 0.146 mm2 vs. 2.232 ± 0.115 mm2, p = 0.013). There was a significant difference between the two groups only for the Δ SCP-VD/parafovea superior value (-0.62 ± 0.98 vs. 1.57 ± 3.07, p = 0.019).

CONCLUSIONS

Conventional horizontal rectus muscle surgeries may cause alterations in posterior segment hemodynamics. The number of muscles incised does not seem to greatly affect the magnitude of changes that occur.

KEY MESSAGES

What is known • After conventional horizontal rectus muscle surgeries, the anterior ciliary arteries are not recanalized, instead, anterior segment blood flow is maintained by increasing the flow in the long posterior ciliary arteries. • Previous studies using Doppler ultrasonography have shown increased flow in the ophthalmic artery, central retinal artery and long posterior ciliary arteries. What is new • In this study, significant increases were observed in superficial and deep capillary plexus-vessel density and choriocapillaris-flow area parameters in the first postoperative month with optic coherence tomography angiography device. • Hemodynamic increases in both retinal and choroidal vasculature were detected in the early period after conventional horizontal rectus muscle surgeries. • The number of muscles incised does not seem to greatly affect the magnitude of changes that occur.

Postoperative outcome and influencing factors of strabismus surgery in infants aged 1-6 years

PURPOSE

To evaluate the postoperative outcome of strabismus surgery performed in children aged 1-6 years by investigating the change of the preoperative angle of deviation (AOD), elevation in adduction, best-corrected visual acuity (BCVA) and refractive error.

METHODS

Retrospective chart review of 62 children who received strabismus surgery between January 2018 and December 2021 at the Department of Ophthalmology and Optometry of the Medical University of Vienna. Age, sex, type of strabismus, AOD, BCVA, refractive error and visual acuity were evaluated with respect to the postoperative outcome.

RESULTS

Mean follow-up was 13.55 ± 11.38 months with a mean age of 3.94 ± 1.97 years (range: 1.0-6.0) at time of surgery. 74.19% of patients (n = 46) had isolated or combined esotropia, 12.90% (n = 8) had isolated or combined exotropia and 12.90% (n = 8) had isolated strabismus sursoadductorius. Mean preoperative AOD of 15.69 ± 16.91°/15.02 ± 14.88° (near/distance) decreased to 4.00 ± 9.18°/4.83 ± 7.32° (near/distance) at final follow-up (p < 0.001). BCVA improved from 0.26 ± 0.26/0.25 ± 0.23 (left/right) to 0.21 ± 0.25/0.20 ± 0.23 (left/right) (p = 0.038). There was no significant change regarding refractive error (p = 0.109) or elevation in adduction (p = 0.212). Success rate which was defined as a residual AOD of less than 10° was 74.19% (n = 46). In 3.23% (n = 2) retreatment was necessary.

CONCLUSION

Strabismus surgery in infants was shown to have a satisfactory outcome with a low retreatment rate. Surgical success rate was not linked to age, sex, type of strabismus or the preoperative parameters AOD, refractive error and visual acuity in this study.

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.

Sequential changes in intraocular pressure during strabismus surgery in patients with thyroid eye disease

BACKGROUND/AIMS

To investigate the sequential change in intraocular pressure (IOP) during strabismus surgery in patients with thyroid eye disease (TED).

METHODS

This prospective study included patients with TED who underwent strabismus surgery (medial rectus [MR], inferior rectus [IR], and superior rectus [SR] recession) between March 2018 and December 2020. The IOP was measured six times during surgery (5 min after intubation, after isolation of the muscle using a hook and dissection of the surrounding tissue, immediately before muscle detachment, immediately after muscle detachment, after reattachment of the muscle, and after closure of the conjunctiva).

RESULTS

Thirty-five eyes of 18 patients were included. The mean IOP at first was 21.1 mmHg, which significantly increased to 28.6 mmHg after muscle isolation. The IOP significantly decreased to 15.5 mmHg after muscle detachment. This increased to 19.1 mmHg after muscle reattachment. The last IOP was 18.9 mmHg. There were similar patterns of sequential change in the IOP among the three muscles. The MR showed the highest increase in IOP. The IR showed the lowest mean IOP compared with the other two muscles.

CONCLUSIONS

The IOP was elevated during the isolation and dissection of the surrounding muscle tissue, especially in the MR. The IOP significantly decreased after muscle detachment and was maintained until the last measurement, even after muscle reattachment. IR showed the lowest IOP among the three muscles during surgery.

Intraocular pressure elevation following the use of topical dexamethasone ointment after squint surgery

Purpose:

To describe the pattern of intraocular pressure (IOP) changes after squint surgery in eyes of black Africans at the University College Hospital, Ibadan, Nigeria.

Materials and Methods:

This was a retrospective review of the clinical records of patients who underwent squint surgery between 2010 and 2019. Data on demographic characteristics, preoperative and postoperative intraocular pressure values, co-existing ocular pathology, type of strabismus, surgery performed, frequency and duration of postoperative topical steroid use and treatment received for elevated intraocular pressure were collected and descriptively summarised.

Results:

Thirty-six (39.1%) out of 92 patients who had squint surgery during the study period met study inclusion criteria. Mean age was 20.5 ± 13.6 years. All patients were administered Maxitrol® ointment postoperatively. Baseline, peak and net change in IOP were 12.9 ± 2.6 mmHg, 21.3 ± 6.8 mmHg and 8.39 ± 7.2 mmHg respectively. Thirty-one (86.1%) patients had elevation in IOP from baseline; 21 (67.7%) of these had significant IOP elevation. Topical steroid therapy was tailed off rapidly for all patients with significant IOP elevation. Twelve patients were commenced on topical IOP lowering medications, with normalization of intraocular pressure in majority of them by three months after surgery.

Conclusion:

Elevated intraocular pressure with the use of topical dexamethasone ointment after squint surgery was common in this study and majority of the patients had significant elevation in intraocular pressure. Close monitoring of the intraocular pressure of black patients, especially children, on topical steroid medication after squint surgery is strongly recommended.

The measurement of ocular axial length in normal human eyes based on an improved Twyman-Green interferometer

In order to meet the demands of myopia prevention, as well as the increasing needs of measurement for refractive and cataract operations in China, a new axial length (AL) measurement system combining an improved Twyman-Green interferometer with digital signal processing has been established. The ALs of 33 eyes of different optical refractive subjects (-8.50 ~ 0.50 D) were measured with the New AL and intraocular lens (IOL) master. The repeatability of measurements with the New AL was assessed using coefficient of variation (CoV) and intra-group correlation coefficient (ICC). Comparison, correlation, linear regression and agreement of AL between devices were analyzed. There was good repeatability (CoV = 0.0617%, ICC = 0.9999) with the New AL and great agreement has been obtained with both devices. These show that the New AL is capable of providing precise AL values over the normal AL range compared to the IOL master, and indicate that the New AL developed can be used for routine clinical AL measurements.

Influence of one or two horizontal muscle surgeries on OCT findings

We investigate the effects of differences between one or two horizontal rectus muscle surgeries (recession ± resection) on the central macular thickness (CMT), subfoveal choroidal thickness (SFCT), and retinal nerve fiber layer (RNFL). Measurements of the CMT, SFCT, and RNFL in patients who underwent horizontal rectus muscle surgery were obtained using optical coherence tomography (OCT). Patients were grouped as those who had undergone rectus muscle recession surgery (Group 1) and those who had undergone rectus muscle recession + resection surgery (Group 2). The CMT, SFCT, and RNFL in patients were measured preoperatively and 1 day, 1 week, 1 month, 3 months, and 6 months postoperatively. A total of 65 eyes of 50 patients were analyzed retrospectively. The average age of the 25 patients in Group 1 was 8.96 ± 7.966 years (min 3, max 38). The average age of the 25 patients in Group 2 was 15.17 ± 6.806 years (min 2, max 34). The comparison of the preoperative and the 1-day and 1-week postoperative values revealed an increase in CMT and SFCT in Group 1 and Group 2. There were no significant differences between the two groups. It was observed that this increase reached the preoperative values after 1-3 months and 6 months in both groups. There was no statistically significant change in the RNFL. Rectus muscle surgery (recession±resection) caused an increase in CMT and SFCT in the early stage, which was possibly caused by the altered choroidal microcirculation resulting from mechanical traction during surgery and by postoperative inflammation. There was no difference between one or two muscle surgeries.

Management of strabismus related to infantile glaucoma: Case series

OBJECTIVE

To evaluate the different modalities of treatment of the strabismus related to infantile glaucoma, its complications, and results.

METHODS

The clinical history of 7 patients with infantile glaucoma which required strabismus surgical treatment were analyzed. Age at onset of glaucoma, type of glaucoma, glaucoma surgeries, type of strabismus, strabismus surgical treatment and postoperative results were studied.

RESULTS

Four patients required strabismus surgery, two were treated with botulinum toxin and one required both. Primary congenital glaucoma was the most common (71,42%), 14,28% had an anterior segment dysgenesis and 14,28% had secondary glaucoma. Regarding strabismus, 4 patients had exotropia and 3 had esotropia. The main difficulty involved the management of the conjunctiva and the filtering blebs.

CONCLUSION

Strabismus is a frequent complication in infantile glaucoma. The management of these patients should be individualized. In our case series, treatment of strabismus improved eye alignment. Surgery should be the mainstay of treatment while preserving the conjunctiva and interfere the less with glaucoma surgeries. Botulinum toxin is a reasonable option when conservative treatment is needed.

Management of strabismus related to infantile glaucoma: Case series

OBJECTIVE

To evaluate the different modalities of treatment of the strabismus related to infantile glaucoma, its complications, and results.

METHODS

The clinical history of 7 patients with infantile glaucoma which required strabismus surgical treatment were analyzed. Age at onset of glaucoma, type of glaucoma, glaucoma surgeries, type of strabismus, strabismus surgical treatment and postoperative results were studied.

RESULTS

Four patients required strabismus surgery, two were treated with botulinum toxin and one required both. Primary congenital glaucoma was the most common (71,42%), 14,28% had an anterior segment dysgenesis and 14,28% had secondary glaucoma. Regarding strabismus, 4 patients had exotropia and 3 had esotropia. The main difficulty involved the management of the conjunctiva and the filtering blebs.

CONCLUSION

Strabismus is a frequent complication in infantile glaucoma. The management of these patients should be individualized. In our case series, treatment of strabismus improved eye alignment. Surgery should be the mainstay of treatment while preserving the conjunctiva and interfere the less with glaucoma surgeries. Botulinum toxin is a reasonable option when conservative treatment is needed.

Intraocular pressure elevation associated with blood in Schlemm's canal after strabismus surgery

Purpose

To report a case of increased intraocular pressure (IOP) associated with blood in Schlemm's canal following strabismus surgery.

Observations

A 43-year-old female presented with acquired comitant esotropia. The patient had undergone an uneventful bilateral medial rectus recession and right lateral rectus resection operation under general anesthesia. Routine post-operative follow-up at day 3 detected a marked chemosis at the temporal side of the conjunctiva, an elevated IOP of 30 mmHg, and the presence of blood in Schlemm's canal in the temporal angle of the right eye. Episcleral venous outflow impairment was hypothesized to be the cause of secondary ocular hypertension in this patient. IOP was controlled with anti-glaucoma drops. Conjunctival chemosis, IOP, and blood in Schlemm's canal gradually decreased, and all topical medications were ceased at 11 weeks after the surgery.

Conclusion and importance

An IOP elevation can be an early complication after strabismus surgery. The presence of blood in Schlemm's canal suggests that the cause is impairment of episcleral venous flow. Although the episode can be transient, this report underlines the importance of IOP examination during the early post-operative period.