Significant hyperopic shift in a patient with extreme myopia following severe hypotonia caused by glaucoma filtering surgery.

INTRODUCTION: To report the case of a high hyperopic refractive shift associated with significant shortening of the ocular axial length following glaucoma filtering surgery.

METHODS: Case report. Patient's records were consulted retrospectively.

RESULTS: A 57-year-old woman, highly myopic, with a history of bilateral intraocular refractive surgery in 1998 (phakic lens ZB5M) and bilensectomy in 2011 (phakic intraocular lens extraction plus cataract surgery with pseudophakic intraocular lens implantation), presented with consistently high intraocular pressure. Despite the treatment with different topical antiglaucomatous medications and good compliance, her intraocular pressure values remained consistently above 20 mmHg. In 2016, the patient was submitted for glaucoma filtering surgery and the mini shunt Ex-Press was implanted in both the eyes (3 months between surgeries). On the first postoperative day, the eyes were hypotonic (intraocular pressure of 5 mmHg) and bilateral macular edema was observed. Three days later, the intraocular pressure in both the eyes reached values higher than 6 mmHg (between 6 and 14 mmHg). Five months after the surgery the macular edema resolved and a significant shortening of the axial length and an important hyperopic refractive shift was observed. When comparing the preoperative and postoperative (18 months) measurements, the variation of the axial length was 2.49 mm in the right eye and 2.19 mm in the left eye; the patient refraction (spherical equivalent) shifted 2.50 diopters in the right eye and 1.75 diopters in the left eye.

CONCLUSION: To the best of our knowledge, we report herein the first documented case of an axial length change of this magnitude after glaucoma filtering surgery.