Clinically significant changes in the spherical equivalent hyperopia in patients with refractive accommodative esotropia

Kanwar Mohan; Suresh Kumar Sharma

doi:10.4103/jcor.jcor_94_21

ORIGINAL ARTICLE

Year : 2022 | Volume : 10 | Issue : 2 | Page : 59-62

Clinically significant changes in the spherical equivalent hyperopia in patients with refractive accommodative esotropia

Kanwar Mohan¹, Suresh Kumar Sharma²
¹ Squint Centre, Chandigarh, India
² Department of Statistics, Punjab University, Chandigarh, India

Date of Submission	16-Jun-2021
Date of Decision	02-Dec-2021
Date of Acceptance	11-Jan-2022
Date of Web Publication	18-Jul-2022

Correspondence Address:
Kanwar Mohan
Squint Centre, SCO: 2467-2468, (1^st Floor), Sector 22-C, Chandigarh - 160 022
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jcor.jcor_94_21

Abstract

Aims: To determine the frequency and factors affecting clinically significant (≥1.0 diopters, D) changes in the spherical equivalent (SE) hyperopia in patients with refractive accommodative esotropia (RAET). Materials and Methods: The medical records of consecutive patients 3–12 years of age with RAET who had cycloplegic autorefraction initially and at follow-ups, initial hyperopia ≥2.0 diopters, and a minimum follow-up of 5 years were reviewed. A difference of ≥1.0D in SE hyperopia between the initial and follow-up/final visits was considered clinically significant. Results: This study included 161 patients (median age, 5 years). The mean follow-up period was 8.7 ± 2.4 years (range, 5.0–17.5 years). Overall, 88 patients (55%) had no clinically significant (<1.0D) change; 65 (40%), ≥1.0D decrease; and 8 (5%), ≥1.0D increase in SE hyperopia between the initial and final visits. Twenty-seven patients (17%) had ≥2.0D decrease and 11 (7%) ≥3.0D. There was no clinically significant change in SE hyperopia in 83% at age ≤7 years, and a ≥1.0D decrease in about 45% after age 12 years and in 3% after age 16 years. A ≥2.0D decrease was more common with initial hyperopia ≥4.0D than with <4.0D (P = 0.001). There was no significant difference between amblyopic and nonamblyopic eyes (P = 0.276). Conclusions: A clinically significant (≥1.0D) decrease in SE hyperopia occurred in 40% and ≥3.0D in 7% of the patients with RAET. Most patients did not have a clinically significant decrease up to age 7 years and after age 16 years. Patients with initial hyperopia ≥4.0D had a more decrease. Amblyopia had no effect.

Keywords: Cycloplegic refraction, hyperopia, refractive accommodative esotropia

How to cite this article:
Mohan K, Sharma SK. Clinically significant changes in the spherical equivalent hyperopia in patients with refractive accommodative esotropia. J Clin Ophthalmol Res 2022;10:59-62

How to cite this URL:
Mohan K, Sharma SK. Clinically significant changes in the spherical equivalent hyperopia in patients with refractive accommodative esotropia. J Clin Ophthalmol Res [serial online] 2022 [cited 2023 Jun 2];10:59-62. Available from: https://www.jcor.in/text.asp?2022/10/2/59/351302

When a child with refractive accommodative esotropia (RAET) is prescribed hyperopic spectacles, the parents often ask whether hyperopia would decrease as the child gets older. The clinician, therefore, should know how frequent is a clinically significant change in hyperopia that warrants a change in spectacle prescription. MacEwen et al.^[1] found that as little as 1.0 diopter (D) reduction in hyperopic correction adversely affected the control of deviation in fully accommodative esotropia. Although there are several studies on the course of spherical equivalent (SE) hyperopia in patients with accommodative esotropia, most investigators^{[2],[3],[4],[5],[6],[7],[8]} reported any amount of change in SE hyperopia without considering whether this change was significant enough to warrant a change in spectacle prescription. To our knowledge, there is only one study^[9] where the investigators analyzed their data considering a difference of ≥1.0 D in SE hyperopia as a significant change. Further, the frequency of 2, 3, or more D decrease of hyperopia, and the age after which a significant decrease is less likely, though of clinical interest, have not been reported. Furthermore, most investigators^{[3],[5],[6],[8],[9]} determined hyperopia on cycloplegic retinoscopy on initial and follow-up visits, and some^[4] combined retinoscopic and autorefractions for the analysis. A cycloplegic autorefraction is known to have greater accuracy and higher reproducibility compared with cycloplegic retinoscopy.^{[4],[10],[11]} We did not find any study on the course of SE hyperopia measured on cycloplegic autorefraction initially and at follow-ups in patients with RAET.

The purpose of this study was to determine^[1] frequency of a clinically significant change (≥1.0D) in SE hyperopia measured on cycloplegic autorefraction initially and at follow-ups in patients with RAET^[2] frequency of 2, 3, or more D decrease of SE hyperopia^[3] the effect of age of the patient, initial hyperopia and amblyopia on the significant decrease of SE hyperopia, and^[4] age of the patient after which a significant decrease of SE hyperopia is less likely.

Materials and Methods

This study was approved by our Institutional Review Board and complied with the tenets of the Declaration of Helsinki. The medical records of consecutive patients diagnosed with RAET (orthophoria/esotropia ≤10Δ at both near and distance with full cycloplegic hyperopic correction) at our clinic between March 1, 2005, and March 31, 2010, were reviewed. Inclusion criteria were patient age 3–12 years at presentation, cycloplegic autorefraction at the initial and follow-up visits, initial SE hyperopia ≥2.0D, and a minimum follow-up of 5 years. Patients who were younger than 3 years or older than 12 years at presentation, had partially RAET, developmental delay, or previous strabismus surgery were excluded. All patients were examined by the same unmasked investigator throughout the follow-up. Spectacles were prescribed for full cycloplegic hyperopic correction initially and at follow-up visits. Amblyopia was treated with occlusion.

Data collected included age at presentation, cycloplegic autorefraction at the initial and follow-up visits, and visual acuity. Visual acuity was assessed using the Snellen distance visual acuity chart in older patients and by binocular fixation pattern in younger patients. A difference of ≥2 Snellen lines between the best-corrected visual acuity of the two eyes in older patients and a lack of alternate fixation in the cover-uncover test in younger patients were considered diagnostic of amblyopia. Cycloplegic refraction was performed with an autorefractor (Huvitz, MR-3100 P, Make-2004, Korea) after instillation of atropine 1% twice a day for 3 days in patients ≤10 years of age and 30 min after 3 instillations of cyclopentolate 1% at 10-min intervals in those >10 years. Three consecutive readings of autorefractor were taken. If there was a difference of >0.50 D between any two readings, again three consecutive readings were taken until the difference between any two readings was ≤0.50 D. The average of three readings was taken as the final reading. We repeated cycloplegic autorefraction on subsequent 6 monthly follow-ups in patients ≤5 years of age and yearly in those >5 years. Cycloplegic refraction was done using the same autorefractor throughout the follow-up period. The calibration of autorefractor was checked every 6 months. The SE hyperopia was calculated as sum of the sphere and one-half of the cylinder power. Anisometropia was defined as a difference of ≥1.50D in the SE hyperopia of the two eyes. We considered a difference of ≥1.0D in SE hyperopia between the initial and follow-up or final visits a significant change, as did Wang, et al.^[9] IBM SPSS Inc., Chicago, IL, USA, version 24.0 was used for statistical analysis. Data were analyzed using the Chi-square test and the Z test for proportions. A P < 0.05 was considered statistically significant.

Results

A total of 5012 medical records were searched. Of these, 3204 records were those of pediatric patients. Out of these 3204 patients, 161 with RAET qualified the inclusion criteria. Those excluded from the study were the patients with RAET who were younger than 3 years or older than 12 years at presentation (1088 patients), had RAET with follow-up of <5 years (942 patients), intermittent exotropia (437 patients), partially RAET (329 patients), pseudoesotropia (108 patients), infantile esotropia (105 patients), or infantile exotropia (34 patients).

Of 161 patients, 117 (73%) were 3–6 years old, 34 (21%) were 7–10 years and 10 (6%) were 11–12 years at presentation. The median age at presentation was 5 years (range, 3–12 years). The mean initial SE hyperopia was 5.52 ± 1.83D in the right eye and 5.68 ± 1.90D in the left eye, and the mean final SE hyperopia was 4.70 ± 1.93D in the right eye and 4.82 ± 2.06D in the left eye. There was no statistically significant difference in the mean initial and final SE hyperopia between right and left eyes (P = 0.44 and P = 0.56, respectively). Therefore, we analyzed data from the right eye only.

The mean SE hyperopia at the initial visit was 5.52 ± 1.83D (range, 2.00–9.50D). Thirty six patients (22%) had a mean SE hyperopia of <4.0D and 125 (78%) had ≥4.0D. Fifty three patients (33%) had amblyopia (strabismic, 40 [25%]; anisometropic, 13 [8%]) at the time of presentation. The mean follow-up period was 8.7 ± 2.4 years (range, 5.0–17.5 years). The average number of follow-ups for cycloplegic refraction was 6.09 ± 2.37 (range, 3.0–12.0).

Overall, on comparing SE hyperopia between the initial and final visits, 88 of 161 patients (55%) had no clinically significant change (<1.0D), 65 (40%) had a ≥1.0D decrease and 8 (5%) had a ≥1.0 D increase. Thirty eight patients (23%) had a decrease of <2.0D, 27 (17%) had a decrease of ≥2.0 D, and 11 (7%) had a decrease of ≥3.0 D. The maximum decrease was 7.0D in one patient (0.6%). The maximum increase of SE hyperopia was 1.75 D in two patients (1%).

The refraction data of 117 patients who initially presented at 3–6 years of age were available at age ≤7 years (105 patients), 7–12 years (116 patients), and >12 years (66 patients). of 105 patients at age ≤7 years, 87 (83%) had no clinically significant change in SE hyperopia, 12 (11%) had ≥1.0 D increase and 6 (6%) had ≥1.0 D decrease. of 116 patients at age 7–12 years, 64 (55%) had no clinically significant change in SE hyperopia, 36 (31%) had ≥1.0 D decrease and 16 (14%) had ≥1.0D increase. of 66 patients at age >12 years, 33 (50%) had no clinically significant change in SE hyperopia, 31 (47%) had ≥1.0 D decrease and 2 (3%) had ≥1.0 D increase.

The refraction data of 34 patients who initially presented at 7–10 years of age were available at age 7–12 years (33 patients) and >12 years (32 patients). of 33 patients at age 7–12 years, 32 (97%) had no clinically significant change in SE hyperopia and 1 (7%) had ≥1.0 D decrease. of 32 patients at age >12 years, 19 (59%) had no clinically significant change in SE hyperopia and 13 (41%) had ≥1.0 D decrease. None of the patients had a ≥1.0D increase of SE hyperopia during the follow-up.

The refraction data of 10 patients who initially presented at 11–12 years of age were available at age >12 years. There was no clinically significant change in SE hyperopia in (60%) of the patients, whereas a ≥1.0 D decrease was seen in (40%). None of the patients had a ≥1 0D increase of hyperopia during the follow-up.

Based on the age of the patient at the last follow-up, the patients were clustered into age groups ≤7 years (48 patients) and >7 years (113 patients). The course of SE hyperopia in relation to the age of the patient at the last follow-up is presented in [Figure 1]. In both groups, SE hyperopia decreased with advancing age. However, this decrease was steeper in patients with ≤7 years of age, compared to that in those with >7 years of age.

Figure 1: The course of hyperopia in relation to the age of the patient at the last follow-up

Click here to view

Overall, 33 of 161 patients (20%) had refraction data available both at ages 16 years and 17–25 years (mean, 18.82 ± 1.99 years). A comparison between SE hyperopia at the initial visit and that at age 16 years showed a ≥1.0 D decrease in 9 of 33 patients (27%). A comparison between SE hyperopia at age 16 years and that at 17–25 years showed a further ≥1.0 D decrease in only 1 of 33 patients (3%, [P = 0.013;95% confidence interval [CI] for difference: 0.080–0.405]).

Twenty-seven of the 125 patients (22%) with initial SE hyperopia of ≥4.0 D had a decrease of ≥2.0 D at the final visit, compared to none of the 36 patients (0%) with initial SE hyperopia of <4.0 D (P = 0.001; 95% CI for difference: 0.144–0.288).

A clinically significant decrease in SE hyperopia was seen in 22 of 53 patients (42%) with amblyopia compared with 43 of 108 patients (40%) without amblyopia, and this difference was not statistically significant (P = 0.837; 95% CI for difference: ‒0.145–0.178).

Discussion

In this study, we considered a difference of ≥1.0D in SE hyperopia between the initial and follow-up or final visits a clinically significant change. Therefore, our results can't be compared with those of other investigators^{[2],[3],[4],[5],[6],[7],[8]} who did not adopt this criterion. Using the criterion mentioned above, Wang, et al. and associates^[9] found no significant change in SE hyperopia in 50%, a significant decrease in 29% and a significant increase in 21% of their patients with a minimum 3 years of follow-up. The corresponding figures in our study were 55%, 40% and 5% with a minimum 5 years of follow-up. Wang, et al. and associates^[9] did not mention how many of their patients had a 2, 3, or more D decrease of SE hyperopia. We found a ≥2.0 D decrease in 17% of patients and ≥3.0 D in 7%. Therefore, the parents may be told these frequencies of the likely amount of decrease of hyperopia in their child. We observed a ≥1.0 D increase in hyperopia in a very small number of patients. We are not sure whether this increase in hyperopia was a true increase or caused by relaxation due to spectacle correction.

Wang et al.^[9] did not find a significant decrease in SE hyperopia before age 7 years. We also had a similar observation in our patients who presented at age 3–6 years. We observed a clinically significant decrease in SE hyperopia after age 12 years in about 45% of our patients irrespective of their age at presentation. Only 3% of our patients had a further significant decrease in SE hyperopia after age 16 years compared to that at 16 years. We, therefore, suggest that the parents may be informed that a significant decrease of hyperopia is less likely after age 16 years.

There is a positive association between a higher initial SE hyperopia and a larger degree of the annual decrease of SE hyperopia.^[12],[13] Park et al.^[5] reported that the decrease in SE hyperopia in patients with initial hyperopia of ≥6.0D was significantly > in <6.0 D. Wang and associates^[9] also found that among anisometropic children, the more hyperopic eye had more myopic shift than the less hyperopic eye. We observed a decrease of ≥2.0D SE hyperopia in a significantly more number of patients with ≥4.0 D hyperopia than in those with <4.0D. This observation supports the previous reports^[5],[9],[11] which stated that higher initial hyperopia tends to show a greater decrease than a lower initial hyperopia over time. In contrast, Esposito, et al. and associates^[14] did not find a significant role of amount of initial hyperopia in the longitudinal change of hyperopia.

Amblyopic eyes are known to show a greater decrease of SE hyperopia compared with nonamblyopic eyes.^[5] Kulp et al.^[15] reported that a greater decrease of hyperopia in the amblyopic eye had a significant correlation with improved ocular alignment suggesting that both motor and sensory fusion promote emmetropization. However, Wang and associates^[9] found that eyes with amblyopia had significantly less myopic shift than those without amblyopia. We did not observe a significant effect of amblyopia on the decrease of SE hyperopia, as also reported by Esposito, et al.^[14]

Raab^[3] found that the course of hyperopia in children with accommodative esotropia was similar clinically to that of the general childhood population of the corresponding age range, whereas Ingram, et al.^[16] suggested that hyperopia behaves differently in strabismic children than in nonstrabismic. Mulvihill, et al.^[8] suggested that elimination of retinal blur by the hyperopic correction in patients with accommodative esotropia could remove stimulus for emmetropization. Similarly, Aurell and Norsell^[17] reported that children with accommodative esotropia treated with spectacle correction of hyperopia maintained or increased their hyperopia, whereas those who had only hyperopia and were not treated with spectacles lost most of their hyperopia. Several investigators^{[13],[18],[19]} have postulated that partial correction of hyperopia may not hinder emmetropization. In contrast, Ingram et al.^[20] reported that children treated with partial correction of hyperopia retained most of their hyperopia compared to those with no treatment. Repka, et al.^[2] postulated that full hyperopic correction for treatment of accommodative esotropia impedes emmetropization. Some investigators^[16],[21] stated that full hyperopic correction may inhibit emmetropization more than partial correction. However, Demirkilinc et al.^[22] found no significant difference in refractive development between partial and full correction of hyperopia in children with accommodative esotropia. In the present study, all patients were treated with full hyperopic correction. Hence, we cannot comment on the comparative effect of full hyperopic correction, partial correction, and no correction on the course of hyperopia in our patients.

This study is limited by its retrospective nature, inconsistent follow-up periods, and the possibility of a bias in recordings of autorefractor readings by a single unmasked observer.

Conclusions

We conclude that there is a clinically significant (≥1.0 D) decrease in SE hyperopia in 40% of the patients with RAET on follow-up. A decrease of ≥3.0 D in SE hyperopia occurs in only 7% of the patients. There is no clinically significant decrease in SE hyperopia up to age 7 years and after age 16 years in the majority of the patients.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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