RESUMO
OBJECTIVE: To describe the inheritance pattern and clinical variability of primary congenital glaucoma (PCG) in a family with two affected siblings. MATERIALS AND METHODS: Two sisters diagnosed at birth with bilateral PCG, whose father had bilateral PCG and mother had bilateral microphthalmus, were subjected to a familial genetic study and ophthalmologic follow-up including intraocular pressure (IOP) measurement, and collection of biometric and cup-to-disc ratio data. RESULTS: The inheritance pattern was autosomal recessive in compound heterozygosis. The sisters were found to be carriers of three pathogenic allele variants of the CYP1B1 gene: c.317C>A (p.Ala106Asp) and c.1345delG (p.Asp449MetfsTer8) in one patient (10 years) and c.1345delG (p.Asp449MetfsTer8) and c.202_209delCAGGCGGC (p.Gln68Serfs153Ter) in her older sister (12 years). Surgical histories included: three goniotomies and two Ahmed valves in each eye, and two trabeculectomies and a pupilloplasty in the right eye in the 10-year old; and one goniotomy, trabeculectomy and three Ahmed valves in each eye in the older sister. Currently, both sisters have a controlled intraocular pressure of 18-20 mmHg in both eyes. The father is blind in both eyes and carries two variants c.317C>A (p.Ala106Asp) and c.202_209delCAGGCGGC (p.Gln68Serfs153Ter). The mother with a single variant c.1345delG (p.Asp440MetfsTer8) has a prosthetic right eye and microphthalmus left eye. CONCLUSIONS: The sisters were found to show two different allelic CYP1B1 variants (compound heterozygosis) with different repercussions on the clinical severity of PCG. These findings highlight the importance of genetic screening of affected families.
RESUMO
Purpose: To measure the in vitro flow properties of the PRESERFLO implant for comparison with the theoretical resistance to flow. Methods: The PRESERFLO was designed to control the flow of aqueous humor according to the Hagen-Poiseuille (HP) equation. Scanning electron microscopy (SEM) was performed to analyze the ultrastructure, and flow measurements were carried out using a gravity-flow setup. Results: SEM images of the PRESERFLO showed luminal diameters of 67.73 × 65.95 µm and 63.66 × 70.54 µm. The total diameter was 337.2 µm, and the wall was 154 µm wide. The theoretical calculation of the resistance to flow (R) for an aqueous humor (AH) viscosity of 0.7185 centipoises (cP) was 1.3 mm Hg/(µL/min). Hence, assuming a constant AH flow of 2 µL/min, the pressure differential across the device (ΔP) was estimated to be 2.6 mm Hg. The gravity-flow experiment allowed us to measure the experimental resistance to flow, which was RE = 1.301 mm Hg/(µL/min), in agreement with the theoretical resistance to flow R given by the HP equation. Conclusions: The experimental and theoretical flow testing showed that the pressure drop across this device would not be large enough to avoid hypotony unless the resistance to outflow of the sub-Tenon space was sufficient to control the intraocular pressure in the early postoperative period. Translational Relevance: The fluid properties of glaucoma subconjunctival drainage devices determine their specific bleb-forming capacity and ability to avoid hypotony and therefore their safety and efficacy profile.