Relationship of inferior oblique overaction to macular and subfoveal choroidal thickness Ismail Ersan, MD, a Refik Oltulu, MD, b Orhan Altunkaya, MD, b Gunhal Satirtav, MD, b Sedat Arikan, MD, a Meryem Donbaloglu, MD, c and Ahmet Ozkagnici, MD b PURPOSE To evaluate the macular and subfoveal choroidal thickness of eyes with inferior oblique muscle overaction (IOOA) using enhanced depth imaging spectral domain optical coher- ence tomography (EDI SD-OCT). METHODS The measurements of macular and subfoveal choroidal thickness obtained by EDI SD- OCT of patients with IOOA (24 patients) were compared with those of age- and sex- matched controls (25 subjects). RESULTS There were no morphological abnormalities of the macula in patients with IOOA or in control subjects. There were no statistically significant differences in macular and subfo- veal choroidal thickness between the eyes with IOOA and the eyes of the control subjects (P . 0.05). When the patients with IOOA were assigned to two distinct groups according to the degree of IOOA, the macular thickness did not differ between groups (P 5 0.66), whereas subfoveal choroidal thickness measures were significantly lower in eyes with severe IOOA compared to eyes of the controls (P 5 0.01). CONCLUSIONS IOOA has no effect on the morphology and the thickness of the macula. Severe IOOA seems to be related to thinning of subfoveal choroid due to possible external mechanical effect. ( J AAPOS 2015;19:21-23) I nferior oblique muscle overaction (IOOA) is a com- mon disorder of ocular motility that may occur as a primary condition or develop secondary to other ab- normalities. 1,2 There is little information evaluating the effect of the inferior oblique muscle force on the macula and choroid where the inferior oblique muscle inserts in the sclera. El Massri 3 found a relationship between the formation of macular holes and the contraction of inferior oblique muscles in patients with high myopia and concluded that the continuous pull of inferior oblique muscle, with some fibers inserted in the sclera, might predispose susceptible patients to retinal tear. Although weakening procedures of inferior oblique muscle are potentially harmful to the macula, Kasem and colleagues 4 reported no morphological abnormalities and no retinal thickness changes detectable on OCT after the weakening procedures. We evaluated the possible effect on the macula of a mechanical force exerted by the inferior oblique muscle. The present study compared the macular and choroidal thickness measurements obtained by EDI SD- OCT of patients with different grades of IOOA and healthy control subjects. Methods This prospective study was performed in accordance with the tenets of the Declaration of Helsinki and with the approval of the ethics committee of the Necmettin Erbakan University School of Medicine. Informed consent was obtained from parents of all before participation. Children diagnosed with inferior oblique overaction from December 2013 to January 2014 at Meram Faculty of Medicine Hospital and an equal number of healthy control subjects were re- cruited for the study. All participants underwent ophthalmic ex- aminations, including best-corrected visual acuity, refractive error, slit-lamp evaluation, extraocular movements, intraocular pressure with pneumatic tonometer (Auto Tonometer TX-F; Canon, New York), and fundus examination. Patients with a neurological disease, history of prematurity or ocular disorders such as hypermetropia exceeding 2 D, myopia and astigmatism exceeding 1 D, glaucoma, nystagmus, retinopathy of prematurity, restrictive strabismus, orbital pathology, previous ocular trauma, history of surgery (except strabismus surgery), and children who were too young to cooperate for OCT scanning, were excluded. According to amount of hypertropia in adduction, IOOA was graded from 11 to 41. For further exploration of the association, we divided the subjects into mild (1 to 21) and severe 3 to 41) Author affiliations: a Department of Ophthalmology, Canakkale Onsekiz Mart University School of Medicine, Canakkale, Turkey; b Department of Ophthalmology, Necmettin Erbakan University School of Medicine, Konya, Turkey; c Department of Ophthalmology, Mus State Hospital, Mus, Turkey Submitted July 18, 2014. Revision accepted September 25, 2014. Correspondence: Ismail Ersan, MD, Department of Ophthalmology, Canakkale Onsekiz Mart University, School of Medicine, Canakkale, Turkey (email: isersan@gmail.com). Copyright Ó 2015 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/$36.00 http://dx.doi.org/10.1016/j.jaapos.2014.09.016 Journal of AAPOS 21