A series of optic disc photographs. A, On June 26, 2002, before trabeculectomy, intraocular pressure (IOP) was 27 mm Hg. B, On July 11, 2002, at 3 days after trabeculectomy, IOP was reduced to 12 mm Hg. C, At 1 week postoperatively, IOP was 9 mm Hg. D, At 3 weeks after surgery, IOP was elevated to 38 mm Hg. E, On April 18, 2003, before needling revision, IOP was 44 mm Hg. F, Two weeks after needling revision, IOP was again reduced to 10 mm Hg.
Kakutani Y, Nakamura M, Nagai-Kusuhara A, Kanamori A, Negi A. Marked Cup Reversal Presumably Associated With Scleral Biomechanics in a Case of Adult Glaucoma. Arch Ophthalmol. 2010;128(1):139-141. doi:10.1001/archophthalmol.2009.339
Reversal of cupping after the reduction of intraocular pressure (IOP) is common in children1 but is also known to occur in adults.2,3 This phenomenon is postulated to be due to a reversal of the backward bowing of the lamina cribrosa, swelling of the optic disc, and increased intravascular volume.2,3 In contrast, recent studies using finite element modeling predict that optic nerve head (ONH) biomechanics strongly depend on scleral biomechanical properties.4,5 In support of this prediction, we report an adult case of secondary glaucoma in which the ONH tissue deformation and restoration due to IOP fluctuation were associated with changes in axial length and optic disc size.
A 21-year-old Japanese man was referred to our institute in June 2002 because of uncontrollably elevated IOP in his right eye after repeated surgical procedures (phacoemulsification, scleral encircling, pars plana vitrectomy, and trabeculectomy) for cataract and rhegmatogenous retinal detachment associated with atopic dermatitis. He had no history or family history of collagenous diseases. At initial examination, his best-corrected visual acuity was 20/200. His IOP was 47 mm Hg as measured with Goldmann applanation tonometry, despite maximally tolerant medical therapy, normal depth of the anterior chamber, open angle, artificial aphakia, a cup-disc ratio of 0.9, and a mean deviation of −19.26 dB on a Humphrey 30-2 program in the right eye. The left eye was normal. Following trabeculectomy with the adjunctive use of mitomycin C, 0.04%, a month later, the IOP fluctuated between 5 and 48 mm Hg owing to filtration blockage and its subsequent release by laser suture lysis and a needling procedure until August 2003, when diode laser cyclodestruction was eventually performed. Although no apparent visual field defect progression or central corneal thickness fluctuation (mean [SD], 532  μm) occurred during this period, enlarging and reduction of cupping correlated with the IOP fluctuation, which accompanied asymmetrical extension and reduction of the disc size (Figure). Therefore, the higher IOP corresponded to a larger disc diameter with more prominent horizontal expansion.
Serial measures of the ONH configuration, axial length, and corneal curvature were conducted using the Heidelberg Retina Tomograph II (Heidelberg Engineering, Heidelberg, Germany) by one of us (Y.K.), the IOL Master version 3.01 (Carl Zeiss Meditec, Jena, Germany), and an autokeratorefractometer (Tomey, Nagoya, Japan), respectively, under approval of the institutional review board of the Kobe University Graduate School of Medicine as previously described (Table).6 Pearson correlation coefficients showed that all Heidelberg Retina Tomograph II cup parameters as well as the photographically determined vertical cup-disc ratio were positively correlated and rim parameters were negatively correlated with the IOP values measured on the same days. Notably, disc size and axial length but not corneal curvature varied with cup size, which was influenced by IOP fluctuation (Table).
Previous studies that also used the Heidelberg Retina Tomograph2 as well as those that used other techniques3 have demonstrated the reversibility of cupping in adult cases of glaucoma. Those studies claimed that the compliance and position of the optic disc and lamina cribrosa were primary determinants for the cup reversal.2,3
Sigal et al4 proposed that elevated IOP deforms ONH tissues indirectly through its influence on the sclera rather than direct action on the internal surface of the ONH. According to them, the highest magnitude of compression occurred within the ONH neural tissues.5 Asymmetrical deformation of the optic disc and axial length fluctuations correlated with IOP under conditions of stable corneal curvature. This may clinically support the idea that scleral biomechanics play a critical role in the reversibility of cupping after IOP reduction. As raised by Lesk et al,2 younger age may contribute to the elastic scleral properties. Meanwhile, the negative correlation of rim parameters with IOP fluctuations may reflect the neural tissue strain and plasticity.
Correspondence: Dr Nakamura, Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, 7-5-2, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan (firstname.lastname@example.org).
Financial Disclosure: None reported.
Funding/Support: This study was partly supported by grants-in-aid 1939044 (Drs Nakamura, Kanamori, and Negi), 20592043 (Drs Nakamura, Kanamori, and Negi), and 19791267 (Dr Kanamori) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.