Background: A V-pattern esotropia with bilateral overaction of the inferior oblique (IO) is a common finding. The clinical characteristics of this condition in a large series are not available. Also, data is lacking about the surgical outcome of graded bilateral inferior oblique recessions. Lastly, it is not known whether patients with a V pattern below 15 prism diopters (pd) should have IO weakening when horizontal eye muscle surgery is to be performed.
Subjects and methods: Seventy-eight consecutive patients without complicating factors were fully evaluated and submitted to bilateral graded recessions of the IO. In Group 1, 59 patients had a V pattern of 15 pd or more; 55 were also operated for a horizontal imbalance. In Group 2, 19 patients in whom a horizontal surgery was required and who also had a V pattern of less than 15 pd, also had a bilateral graded recession of the IO performed.
Results: Preoperative findings: In Group 1, the distribution of V patterns showed 88.1% in the range 15 to 35 pd. A bilateral overaction of the IO, a bilateral underaction of the superior oblique (SO), and elevation in adduction OU were present in 62.7% of the patients. A vertical imbalance was observed in 20.3%. In Group 2, a bilateral overaction of the IO, a bilateral underaction of the SO, and elevation in adduction OU were noticed in 42.1% of the patients. A vertical deviation was seen in 26.3%. After surgery, in Group 1, 83% had less than 15 pd of V pattern or less than 10 pd of A pattern. Surgery reduced a presurgical vertical imbalance, but created a vertical deviation in some cases devoid of hypertropia before surgery. After surgery in Group 2, a full correction or undercorrection was obtained in 63.1% of the patients and an overcorrection to an A pattern in 21.0% Surgery was also prone to induce a vertical deviation. Binocularity: There was an improvement of the fusional status with surgery, (ascertained with the Worth Four Dot Test and major amblyoscope measurement), in patients of both Groups 1 and 2.
Conclusion: In V-pattern esotropia cases of 15 pd or more the vast majority were in the range 15-35 pd. Overaction of both IO, underaction of both SO, and elevation in adduction OU constituted a triad of co-occurrent signs present in a significant number of patients. A vertical imbalance was detected in 1/5 of the cases. A good outcome (collapse of the V pattern) was obtained with bilateral graded recession of the IO, but this surgery can create a vertical imbalance. In cases of V pattern less than 15 pd, and requiring horizontal surgery, weakening of both IO's can be advised.