The Contribution of Anterior Segment Abnormalities to Changes in Intraocular Pressure in the DBA/2J Mouse Model of Glaucoma: DBA/2J-Gpnmb +/SjJ Mice as Critical Controls.

The contributions of anterior segment abnormalities to the development of ocular hypertension was determined in the DBA/2J mouse model of glaucoma. Intraocular pressure (IOP) was measured non-invasively. Iris pigment dispersion (IPD) and corneal calcification were measured weekly starting at 20 weeks of age in DBA/2J and DBA/2J-Gpnmb +/SjJ mice. Thickness, surface area, auto-fluorescence intensity, and perimeter length of calcified regions were measured in postmortem corneas using confocal microscopy. DBA/2J mice developed elevated IOP between 9 and 12 months of age, but DBA/2J-Gpnmb +/SjJ mice did not. Corneal calcification was found at all ages observed and at similar frequencies in both strains with 83.3% of DBA/2J eyes and 60.0% of DBA/2J-Gpnmb +/SjJ eyes affected at 12 months (P = 0.11). Calcification increased with age in both DBA/2J (P = 0.049) and DBA/2J-Gpnmb +/SjJ mice (P = 0.04) when assessed qualitatively and based on mixed-effects analysis. No differences in the four objective measures of calcification were observed between strains or ages. At 12 months of age, DBA/2J mice with corneal calcification had greater mean IOP than DBA/2J mice without corneal calcification. IOP was not correlated with the qualitatively assessed measures of calcification. For the subset of eyes with ocular hypertension, which were only found in DBA/2J mice, IOP was negatively correlated with the qualitative degree of calcification, but was not correlated with the four quantitative measures of calcification. Differences in IOP were not observed between DBA/2J-Gpnmb +/SjJ mice with and without calcification at any age. IPD increased with age and demonstrated a moderate correlation with IOP in DBA/2J mice, but was not observed in DBA/2J-Gpnmb +/SjJ mice. In the DBA/2J mouse model of glaucoma, increased IPD is positively correlated with an increase in IOP and corneal calcification is present in the majority of eyes at and after age 9 months. However, while IPD causes ocular hypertension, corneal calcification does not appear to contribute to the elevation of IOP, as the control strain DBA/2J-Gpnmb +/SjJ exhibits corneal calcification similar to DBA/2J mice, but does not develop ocular hypertension. Corneal calcification, therefore, does not appear to be a contributing factor to the development of elevated IOP in DBA/2J mice.

A Novel Hinged Scleral Patch Graft for the Repair of Overfiltration and Bleb Leaks.

INTRODUCTION: The repair of the scleral flap is often needed in cases of severe hypotony or bleb leaks with overfiltration. We present a simple novel technique to restore the hinged flap using a scleral patch graft. MATERIALS AND METHODS: We present 4 eyes of 4 patients who presented with hypotony [intraocular pressure(IOP) <6 mm Hg] from overfiltration secondary to loose scleral flap (2 eyes) and bleb leak (2 eyes). A scleral patch from a human donor, preserved in 95% ethanol, was cut in a trapezoidal shape and placed over the area of filtration after a conjunctival peritomy. The scleral graft was secured anteriorly with a single double-armed 9-0 nylon suture in a double-mattress manner so as to create a hinged flap. Permanent or releasable sutures were placed posteriorly to control aqueous outflow. RESULTS: All 4 patients had complete resolution of hypotony and bleb leaks with increase in their IOP to early teens. All maintained aqueous flow posteriorly with preservation of bleb function. CONCLUSION: Reestablishing the original anatomy of the hinged scleral flap can maintain bleb function without risk of overfiltration or loss of IOP control. This can be achieved through a simple repair using a scleral patch graft.

Slit-lamp Needling of the Anterior Capsule for Aqueous Misdirection After Hyaloido-zonulectomy and Iridectomy.

INTRODUCTION: We present a case of persistent aqueous misdirection, after Ahmed glaucoma valve surgery, despite undergoing an anterior vitrectomy with hyaloido-zonulectomy and iridectomy. CASE REPORT: A 73-year-old female patient, 4 months after phacotrabeculectomy, was referred with persistent high intraocular pressure (IOP). Postoperatively, she developed aqueous misdirection with a flat anterior chamber (AC) but with an IOP of 15 mm Hg. On presentation, her AC was shallow with peripheral iris-cornea touch, and her IOP was 39 mm Hg. Posterior Nd:Yag capsulotomy with disruption of anterior hyaloid face partially deepened the AC. With failure of the trabeculectomy and high IOP, an Ahmed valve was placed. On the first operative day the AC was deep with an IOP of 10 mm Hg. On day 6 the patient presented with pain, flat AC, and an IOP of 10 mm Hg. Fundus examination revealed no choroidal effusion. Despite repeated reformation with viscoelastic, the AC failed to deepen. An anterior vitrectomy with hyaloido-zonulectomy was performed. Initially, the AC was deep, but, a few days later, it was flat. Multiple reformations and vitreous tap failed to keep the AC deep. A 30-G needle was passed at the slit lamp across the temporal cornea, iris, and anterior capsule into the anterior vitreous cavity. The needle was then partially withdrawn and used to create a space between the intraocular lens and anterior capsule. This immediately deepened the AC and remained so for the duration of follow-up (4 mo). CONCLUSION: Slit-lamp needling of the anterior lens capsule can be successfully performed to help resolve a persistent case of aqueous misdirection after anterior vitrectomy.