Childhood esotropia is commonly associated with significant hypermetropia. Depending upon the effect of spectacle correction, esotropia is further classified. If significant esotropia persists despite refractive correction, a prompt surgical correction offers a better chance to restore binocularity and stereoacuity.[2–4] This study was performed to test our hypothesis that cycloplegia abolishes the accommodative component of esotropia that helps to anticipate the effect of refractive correction on the ocular deviation. Literature search did not reveal a pertinent peer reviewed study.
Materials and Methods
This cohort study included 44 consecutive patients with the following inclusion criteria: (1) age 1-16 years, (2) comitant esotropia ≥ 12 prism diopters (Δ), (3) hyperopia ≥ +2.0 diopters (D; spherical equivalent), (4) patients cooperative for reliable measurement of ocular deviation, (5) minimum 3-month follow-up, and (6) 100% compliance to spectacle wear. Exclusion criteria were (1) associated ocular comorbidity, namely, coloboma, nystagmus, albinism, or cataract, (2) poor fixation, and (3) systemic abnormalities, namely, birth asphyxia, cerebral palsy, or Down's syndrome.
Deviation was measured with the prism cover test using the age appropriate accommodative target for near (40 cm) and distance (6 m). The measurements were taken at (1) presentation, without optical correction and without cycloplegia; (2) after 3 days, under complete cycloplegia, without optical correction; and (3) after 3 months of spectacle wear with full refractive correction and without cycloplegia.
In patients with convergence excess (CE), the near deviation was measured with +3.0 D addition. In children < 3 years (n = 7), the corneal reflex test by Krimsky's method was utilized to measure the distance deviation.
Cycloplegia was achieved with 1% atropine eye ointment applied twice a day for 3 days and once on the day of examination (fourth day).
A child was diagnosed with refractive accommodative esotropia (RAE) if the deviation was corrected to <10 Δ with spectacles [Fig. 1]; partial accommodative esotropia (PAE) if there was a significant reduction of the deviation (≥10 Δ) with spectacles, yet there was a residual esotropia of ≥10 Δ [Fig. 2]; and nonaccommodative esotropia (NAE) if spectacle correction did not have a significant effect on the deviation [Fig. 3]. CE was diagnosed when the near deviation exceeded the distance deviation by ≥8 Δ [Figs. 4–6].
The ocular deviation under cycloplegia was compared with the ocular deviation after spectacle correction (+3.0 D addition for the near in patients with CE). Pearson's correlation coefficient (r) and intraclass correlation coefficient (ICC) were calculated to assess the correlation.
The sample size was calculated using the formula N = (z1-α/2 – z1-β)2sd2/d2. At 5% significance and 90% power of the study, to detect the difference of 4 Δ, with a standard deviation of difference 8 Δ, we needed 42 subjects.
Forty-four children aged 5.2 ± 2.4 years (SD, range 1-9) of whom 25 were males were included. RAE was the most common type of esotropia [Table 1]. All patients with RAE and RAE with CE had orthotropia under cycloplegia [Table 2]. In PAE, the deviation measured under cycloplegia was equal to that measured with full refractive correction. In PAE with CE, the deviation measured under cycloplegia was equal to that measured with full refractive correction with +3.0 D addition. In the patients with NAE, the deviation measured under cycloplegia was same as that with spectacle correction.
A child with NAE with CE (nonaccommodative CE) with emmetropia (not included in the study) had orthotropia with the bifocals but esotropia for near under cycloplegia [Fig. 6].
r for the ocular deviation under cycloplegia and full refractive correction (with +3 D addition in the patients with CE) was 1.0. The ICC was excellent (0.89).
Three patients required oral medication for fever. None had to discontinue atropine.
An accommodative esotrope often has straight eyes when not accommodating. Similarly, under complete cycloplegia, the accommodative component of the esodeviation is eliminated. Hence the ocular deviation under cycloplegia was useful to predict the effect of spectacle correction on ocular deviation.
In a previous study, “in patients with RAE, hyperopic LASIK produced orthotropia when there was postoperative emmetropia and in patients with PAE, residual esotropia remained despite a postoperative emmetropia.”
We treated a 3-year-old child with RAE and amblyopia, whose esotropia disappeared after bilateral cataract surgery with intraocular lens implantation, despite a postoperative hyperopia of +1.75 D in both eyes.
It seems, in patients with accommodative esotropia, the central will to accommodate disappears with the full refractive correction of hyperopia/addition lenses if there is CE, after cataract extraction and under complete cycloplegia.
Complete cycloplegia for a prolonged duration is an absolute prerequisite for reliable measurements. With incomplete cycloplegia or shorter duration of cycloplegia, an accommodative effort may still be deployed resulting into an esodeviation. A clinician should routinely perform dynamic retinoscopy and give adequate time for the cycloplegia to persist.
In one patient with NAE with CE (hypoaccommodative convergence excess), the esotropia persisted under cycloplegia [Fig. 6]. We confirmed complete cycloplegia using dynamic retinoscopy and dynamic autorefractometry. It was evident that atropine for three days was unable to abolish excessive convergence. A similar observation was reported by Nemet. Probably the nonaccommodative/hypoaccommodative CE in these patients makes it impossible to block the convergence drive for near fixation even under cycloplegia after two days. Such patients need cycloplegia for a longer duration.
We examined two of the PAE patients nearly 3 years prior to their recruitment in this study. At that time, they had RAE. They demonstrated orthotropia under cycloplegia during the RAE stage and residual esotropia during the PAE stage. Another patient (not included in the study) had RAE that rapidly decompensated to NAE; she had orthotropia under atropine during the RAE stage and large esodeviation under atropine during the NAE stage [Fig. 7]. Another child with +6.0 D in both eyes and intermittent exotropia developed consecutive RAE; after squint surgery (not included in the study) he demonstrated an orthotropia with full refractive correction and under complete cycloplegia [Fig. 8]. In conclusion, cycloplegia abolished the accommodative component of esotropia. The measurement of deviation under cycloplegia could be helpful to differentiate the accommodative component from the nonaccommodative component in patients with esotropia and hyperopia.
Further studies are necessary to know whether or not the residual esotropia under cycloplegia will be controlled with fusional divergence once the deviation is reduced with spectacle correction and the effect of other cycloplegic agents.
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