Efficacy of prism adaptation in the surgical management of acquired esotropia

Prism and Maddox rod test as a reliable tool for surgical targeting in small-angle AACE

This retrospective study aimed to evaluate the efficacy of the prism and Maddox rod test (PMT) in determining surgical targets for small-angle acute acquired concomitant esotropia (AACE). Thirty-three patients with small-angle AACE who underwent surgical treatment at the First Affiliated Hospital of Fujian Medical University from June 2017 to May 2023 were included. All patients underwent various tests, including the Hirschberg test (HT), PMT, and prism and alternative cover test (PACT). PACT measured the minimum value (PACTmin) and the maximum value (PACTmax) based on different interpretation criteria for examination endpoint. PMT results were used as the surgical target. Unilateral medial rectus recession (MRrec) was performed on all patients, and postoperative follow-up lasted up to 6 months to evaluate deviation angle and binocular vision. Both near and distance measurements from PMT were 23.67 ± 5.44 PD and 24.82 ± 5.49 PD, respectively, which were comparable to PACTmax (23.06 ± 2.65 PD and 23.58 ± 2.35 PD) and significantly higher than PACTmin (15.18 ± 5.12 PD and 15.24 ± 5.06 PD; P < 0.001). Post-surgery, the mean deviation angles for distance and near viewing were reduced to 0.73 ± 1.69 PD and 0.61 ± 1.35 PD (PMT and PACTmin, respectively). All patients achieved excellent surgical outcomes, with no noticeable deviation angles, diplopia disappearance, and restoration of normal binocular vision. Our study demonstrates that PMT serves as a reliable and practical method for determining surgical targets in patients with small-angle AACE. The results highlight its accuracy and consistency in measuring deviation angles, which can effectively guide unilateral MRrec.

Prism adaptation test before strabismus surgery in patients with decompensated esophoria and decompensated microesotropia

Purpose

To evaluate the effect of Prism adaptation test (PAT) on the angle of squint in decompensated esophoria (decEPH) and decompensated microesotropia (decMET).

Methods

In this single-center retrospective study we reviewed the medical records of patients with the diagnosis of decEPH or decMET, aged at least 12 years, who were treated by strabismus surgery for the first time. The maximum Angle of squint (AOS) for far (F) and near (N) fixation and PAT results before surgery, as well as AOS (F) and AOS (N) after surgery and results of binocular function tests were considered. PAT included wearing a prism based on the largest angle for over 60 min.

Results

100 patients (mean age 37 ± 17 years) were included in the decEPH group, 82 patients (mean age 30 ± 13 years) in the decMET group. For decEPH, before surgery AOS was 25.5 ± 8.8 pdpt (F) and 23.5 ± 9.8 pdpt (N). During PAT the AOS increased significantly by 2.7 ± 4.3 to 28.2 ± 8.6 pdpt (F) and by 4.9 ± 4.5 to 28.3 ± 9.5 pdpt (N). Altogether, in 82% of decEPH patients AOS (F) and/ or AOS (N) in- or decreased by at least 3 pdpt. For decMET, before surgery AOS was 28.6 ± 10.8 pdpt for far (F) and 30.9 ± 11.8 pdpt for near fixation (N). During PAT the AOS increased significantly by 4.2 ± 5.8 to 32.5 ± 9.5 pdpt (F) and by 3.7 ± 6.1 to 34.4 ± 9.5 pdpt (N). Altogether, in 51% of decMET patients, AOS (F) and/ or AOS (N) increased by at least 10 pdpt, therefore more than 5° which would have been maximally expected from mictrotropia, or decreased by at least 3 pdpt.

Conclusions

The Prism adaptation test (PAT) showed remarkable changes in AOS in both decEPH and decMET. In patients with decEPH, the preoperative assessment of the “true AOS” under PAT reflects a pivotal requirement for successful strabismus surgery, as 82% had dose relevant angle changes ≥ 3 pdpt. For patients with decMET the preoperative prism adaptation test is especially of diagnostic value, but also 51% of decMET patients had changes in AOS beyond the expected microtropic angle (≥ 10 pdpt) or even a dose relevant angle decrease (≥ 3pdpt).

Comparison of the therapeutic effects of surgery following prism adaptation test versus surgery alone in acute acquired comitant esotropia

BACKGROUND

To compare the therapeutic effects of surgery following prism adaptation test versus surgery alone in acute acquired comitant esotropia (AACE).

METHODS

A total of 46 patients with AACE were enrolled in this retrospective study. Among them, 26 patients underwent surgery following prism adaptation test (combination group) and 20 patients underwent surgery alone (surgery group). The following parameters were evaluated including success rate, distant and near deviation angles, visual function, and near stereoacuity.

RESULTS

There were no significant differences in success rate between the combination group and surgery group at post-treatment 12 months (96.15% vs. 90.00%, p > 0.05). The postoperative distant and near deviation angles in two groups were significantly lower than that before surgery (p < 0.05). In addition, the numbers of patients with stereopsis postoperatively in two groups were significantly higher than that before surgery (all p < 0.05). Moreover, the numbers of patients with stereopsis and central stereopsis in the combination group were significantly higher than that in the surgery group postoperatively. At post-treatment 12 months, one (3.85%) case recurred in combination group and three (15.00%) cases in the surgery group. No complications were observed in the two groups.

CONCLUSIONS

Both approaches had therapeutic benefit in AACE. Surgery following prism adaptation test had better treatment benefits than surgery alone in improving binocular function and reducing recurrence rate.

Long-term outcomes of prismatic correction in partially accommodative esotropia

Purpose

In partially accommodative esotropia (PAET), prism glasses can correct small angles of residual esotropia but the long-term effect of prismatic correction alone without surgery has not been reported. We aimed to investigate the long-term outcome of prism glasses after full hypermetropic correction for PAET.

Methods

This retrospective, case-control study was performed for children aged 10 years or younger with a residual esotropia of ≤ 20 prism diopters (PD) after full hypermetropic correction who were fitted with prism glasses and followed-up for 3 years or more. Clinical characteristics and the angle of esodeviation were obtained at each follow-up examination. Successful motor outcome after 3 years of prismatic correction was determined if the residual angle of esotropia after full hypermetropic correction was ≤ 10PD. Patients who eventually weaned off prism glasses were noted.

Results

Among 124 patients, 30.6% achieved success and 7.3% weaned off prism glasses after 3 years of prism-wear. Smaller amount of latent esodeviation (P = 0.001) revealed by prism adaptation and good fusional response at near with the Worth 4-dot test were significant prognostic factors of success by multivariate analysis (P = 0.033). After 3 years of wearing prism glasses, the rate of improvement in stereoacuity was higher in the Success group (60.5% vs 27.9%) (P = 0.001), however, there was no significant difference between the prism-weaned group and prism-wearing group within the Success group (P>0.05).

Conclusion

Prism glasses for small angle PAET can be a treatment option in patients who have a small angle of latent esodeviation revealed by prism adaptation and good sensory fusion at near. Otherwise, early surgery may be advisable as the majority of patients showed suboptimal outcome even after long-term prism-wear.

Short prism adaptation test in patients with acquired nonaccommodative esotropia; clinical findings and surgical outcome

PURPOSE

To evaluate the surgical outcomes in patients with acquired nonaccommodative esotropia operated on based on a short prism adaptation test (PAT) and to determine the subgroup of patients most responsive to PAT.

METHODS

In this prospective interventional cases series, patients with acquired nonaccommodative esotropia were enrolled. Patients wore Fresnel trial lenses based on the results of alternate prism-cover testing. With the Fresnel prism in place, alignment was measured after 20 minutes. If deviation increased, the power of prism was increased to neutralize this angle. The test was repeated every 20 minutes to achieve motor stability. Patients were classified as either prism responders (if the angle of deviation increased >10^Δ compared to the entry angle) or prism nonresponders. All patients underwent bilateral medial rectus muscle recession. Prism responders underwent surgical correction based on the enhanced angle.

RESULTS

Of the 28 subjects enrolled, 14 (50%) were prism responders and 14 (50%) were classified as prism nonresponders. After 6 months, 100% of prism responders and 92.9% of nonresponders were aligned within 8^Δ of orthotropia at distance and near fixation. None of the patients with an entry angle of >30^Δ were prism responders.

CONCLUSIONS

In our study cohort, a short PAT with an endpoint of motor stability in patients with acquired nonaccommodative esotropia was associated with a good surgical outcome and a low rate of over- and undercorrection. PAT may be unnecessary for patients with an angle of deviation of >30^Δ.

Preoperative prism adaptation for acquired esotropia: long-term results

PURPOSE

The efficacy of preoperative prism adaptation in subjects with acquired esotropia has been established at 6 and 12 months postoperatively. We evaluated the outcomes of subjects with acquired esotropia who had preoperative prism adaptation and were followed longer than 12 months.

METHODS

A retrospective analysis was undertaken of 2 groups of subjects with acquired esotropia who underwent bilateral medial rectus recessions based on the distance angle of deviation and were followed more than 12 months postoperatively. Group A subjects had preoperative prism adaptation to determine the target angle for corrective surgery. In Group B subjects, surgery was based on the maximum angle of strabismus at distance, determined by alternate prism cover test without preoperative prism adaptation.

RESULTS

We compared 17 subjects in Group A and 19 subjects in Group B. The postoperative follow-up period was 3 +/- 1.7 years in Group A and 4.8 +/- 1.8 years in Group B. The age at the last visit was 9.1 +/- 2 years in Group A and 10 +/- 2 years in Group B. Postoperative residual esotropia was 2.6 +/- 2.5 PD at distance in Group A patients and 6.6 +/- 5.9 PD in group B patients (P =.002). Residual esotropia at near was 3 +/- 3.8 PD in Group A and 11.5 +/- 8.12 PD in Group B (P <.01). More Group B subjects required bifocal spectacles to achieve optimal alignment at near (P =.001).

CONCLUSION

Acquired esotropia subjects operated on for their distance prism-adapted angle maintained better motor alignment over a long-term follow-up period when compared with nonprism-adapted subjects operated on for their distance angle.