Polyethylene Glycol-Based Synthetic Hydrogel Sealant for Filtration Bleb Leaks: An In Vivo and Histologic Study.

Purpose: To evaluate the efficacy of polyethylene glycol (PEG)-based synthetic sealant for closing bleb leaks after glaucoma filtration surgery. Methods: Tube shunt surgery that included implantation of a 22-gauge indwelling catheter and intraoperative mitomycin C was performed in the left eyes of 11 New Zealand white rabbits. Seven days postoperatively, all filtration blebs were perforated with an 18-gauge needle to create a bleb hole. In six rabbits, the holes were covered with the sealant and irradiated with blue-green light for 60 seconds; in the five control rabbits, the holes were untreated. For 3 weeks after the tube shunt surgery, the eyes were checked for bleb leaks, and the intraocular pressure (IOP) was measured in both eyes. Finally, the operated eyes were enucleated for histologic examination. Results: The bleb leaks stopped in the eyes in which sealant was used and persisted in the other eyes. The sealant preserved the bleb function; the IOPs in these eyes were significantly (P < 0.05) lower than the right eyes that did not undergo surgery. Hematoxylin and eosin staining showed that the holes were closed and covered with conjunctival epithelial cells in the eyes in which sealant was applied; the holes were open in the control eyes. Immunohistochemical staining showed that the bleb holes in which the sealant was applied had fewer inflammatory cells. Conclusions: The PEG sealant has the potential to seal bleb leaks effectively. Translational Relevance: Application of the PEG sealant can be used as adjunct therapy for bleb leaks in glaucoma surgery.

Patching retinal breaks with polyethylene glycol-based synthetic hydrogel sealant for retinal detachment in rabbits.

The purpose of this study was to evaluate absorbable polyethylene glycol (PEG)-based synthetic hydrogel as a sealant for retinal breaks in rhegmatogenous retinal detachment (RD). A three-port, 25-gauge vitrectomy was performed on nine Dutch pigmented rabbit eyes. Subsequently, RD was induced by creating a retinal break. The retina was then reattached by fluid-air exchange. In six of nine eyes (RD-PEG group), PEG sealant was applied to completely cover the retinal breaks, and then photopolymerized with light; thereafter, intravitreous air was replaced with balanced salt solution (BSS). In the remaining three eyes (RD group), PEG sealant was not applied, but the intravitreous air was replaced with BSS. Ophthalmological examinations and intraocular pressure measurements were conducted preoperatively, and at 1 and 7 days, and 1, 3, and 6 months postoperatively. Histological examinations of the eyes were performed after 6 postoperative months. At surgery, retinal reattachment with PEG sealant was achieved in all eyes in the RD-PEG group. Fundoscopic and optical coherence tomographic examinations revealed that the retina remained attached in all the eyes of the RD-PEG group throughout the 6-month observation period. Histological examination revealed no signs of damage in the retinal layers at the edges of the retinal breaks that were in contact with the sealant. In the RD group, the retinas detached in all eyes within 7 days postoperatively. The PEG sealant closed the retinal breaks and maintained retinal reattachment. Intraocular tamponade was not necessary.

Polyethylene Glycol-Based Synthetic Hydrogel Sealant for Closing Vitrectomy Wounds: An In Vivo and Histological Study.

PURPOSE: We conducted an in vivo study using Dutch pigmented rabbit eyes to test the usefulness of polyethylene glycol (PEG) sealant for the closure of sutureless sclerotomies in microincisional vitrectomy surgery (MIVS). METHODS: Three-port, 23-gauge vitrectomy was performed on rabbit eyes. After air leakage was confirmed by the application of 0.625% povidone-iodine at the sclerotomy site, PEG sealant was subconjunctivally injected using a 27-gauge needle through conjunctival incisions to cover the sclerotomy wounds, following which it was polymerized by the application of xenon light for 60 seconds. Ophthalmological examinations and intraocular pressure measurements were conducted the day before and 1, 3, 5, and 7 days after surgery. The eyes were enucleated for histological evaluation 7 days after surgery. RESULTS: PEG sealant was rapidly polymerized by the application of xenon light after subconjunctival injection, and it firmly sealed the sclerotomies without air leakage, as confirmed by povidone-iodine dropping, in all cases. Conjunctival and scleral wounds closed with PEG sealant were successfully attached and remained intact till the end of the follow-up period. There was no sign of postoperative hypotony or infection in any eye, and no adverse effects of PEG sealant were found. In histological examination, linear scar formation and eosinophilic staining of collagen fibers were observed at the sclerotomy sites, while the sclerotomy tunnels appeared tightly closed. CONCLUSIONS: PEG sealant can be useful for the closure of sutureless 23-gauge vitrectomy incisions in rabbits. TRANSLATIONAL RELEVANCE: The PEG sealant may become an effective option for closing vitrectomy incisions including pediatric cases.

In Vivo and In Vitro Feasibility Studies of Intraocular Use of Polyethylene Glycol-Based Synthetic Sealant to Close Retinal Breaks in Porcine and Rabbit Eyes.

PURPOSE: Absorbable polyethylene glycol-based synthetic sealant (PEG sealant) polymerizes under xenon illumination and forms a clear, flexible, and firmly adherent hydrogel. The intraocular biocompatibility of PEG sealant and efficacy for closing retinal breaks were evaluated. METHODS: In an in vitro study, retinal detachment with a tear was created in porcine eyecups after vitreous gel removal. Polyethylene glycol-based synthetic sealant was applied to cover the tear and polymerized with a 40-second application of xenon light. Retinal adhesion strength was tested by forcefully squirting balanced salt solution (BSS) onto the retinal tear. Polyethylene glycol-based synthetic sealant was soaked in the BSS, incubated at 37°C, and the pH measured periodically over 72 hours. In an in vivo study, PEG sealant was injected into the vitreous cavity of the left eyes of rabbits. Ophthalmologic examinations were performed and bilateral ERGs were recorded simultaneously before and 28 days after injection. The eyes were enucleated for histological evaluation. RESULTS: Adhesion of PEG sealant to the retina was good in BSS. A forceful squirt of BSS onto the retinal tear covered with PEG sealant did not detach the retina; the retinal tear without PEG sealant detached immediately. The pH of the BSS containing PEG sealant was between 7.2 and 8.2. No inflammatory reaction was observed in the eyes throughout 28 days of follow-up. The ERGs recorded before and after injection showed typical patterns. Histological examinations did not reveal any abnormality or inflammation. CONCLUSIONS: Polyethylene glycol-based synthetic sealant appeared to effectively seal retinal breaks and was not toxic to the eye.

Multifocal electroretinograms in Stargardt's disease/fundus flavimaculatus.

PURPOSE: To determine whether the characteristics of multifocal electroretinograms (mfERGs) were correlated with the ophthalmic appearance of the fundus in patients with Stargardt's disease/fundus flavimaculatus (SFF). METHODS: Full-field ERGs, mfERGs, and general ophthalmic examinations were performed on 49 eyes with SFF. RESULTS: The SFF patients were divided into four subtypes according to the classification of Noble and Carr [Arch Ophthalmol 1979;97:1281-1285]. The patients with type 1 SFF had severely reduced mfERGs in the macular area and reduced and delayed responses in the mid-periphery. The type 2 SFF patients had reduced but recordable mfERGs from the center of the macula with more depressed responses in the paramacular area, and the type 3 SFF patients had reduced and delayed mfERGs both in the macula and periphery. The patients with type 4 SFF had normal mfERGs in the macular area and delayed responses in all outer zones. CONCLUSIONS: These mfERG findings indicate that each subtype of SFF has unique characteristics corresponding to the abnormal retinal functions.

Retinal nerve fiber layer thickness changes following optic neuritis caused by multiple sclerosis.

PURPOSE: To evaluate the peripapillary retinal nerve fiber layer (RNFL) thickness with scanning laser polarimetry in patients with optic neuritis (ON) caused by multiple sclerosis. METHODS: Peripapillary RNFL thickness was measured with a GDx VCC in 14 eyes of 13 patients with ON (nonrecurrent group), in 18 eyes of 11 patients with recurrent ON (recurrent group), and in 48 eyes of 48 healthy subjects (healthy group). The temporal, superior, nasal, inferior thickness (TSNIT) average, superior average, and inferior average of GDx VCC measurements were compared across the three groups. We calculated correlation coefficients between each of the three GDx VCC parameters and both the mean deviation (MD) of the Humphrey 30-2 full threshold visual field and the visual acuity (VA). RESULTS: The three parameters showed statistically significant differences across the three groups. There was no correlation between any of the three GDx VCC parameters and MD or VA in the nonrecurrent group, but there was significant correlation between each of the three GDx VCC parameters and MD in the recurrent group. CONCLUSIONS: ON caused morphological changes in the peripapillary RNFL, and recurrent ON aggravated the deterioration and caused diffuse rather than regional damage to the peripapillary RNFL.

Seprafilm as a new antifibrotic agent following trabeculectomy in rabbit eyes.

PURPOSE: To investigate the efficacy of Seprafilm (Genzyme, Framingham, MA, USA) in preventing postoperative adhesion between the conjunctiva and sclera after glaucoma filtering surgery. METHODS: A subconjunctival pocket was created and Seprafilm was inserted into the pocket in nine rabbits (Seprafilm group), whereas in a second group, a subconjunctival pocket was created in nine rabbits but no Seprafilm was inserted (non-Seprafilm group). The postoperative adhesion force was measured 4 weeks after surgery. For the trabeculectomy study, trabeculectomy was performed and Seprafilm placed on the scleral flap in five rabbits (Seprafilm trabeculectomy group), whereas in a second group, trabeculectomy was performed in five rabbits but no Seprafilm was placed (non-Seprafilm trabeculectomy group). Filtering bleb formation and intraocular pressure (IOP) was evaluated on days 1, 3, 5, 7, 14, 21, and 28 following surgery. The eyes were enucleated for histologic evaluation 4 weeks after surgery. RESULTS: The mean adhesive force between the conjunctiva and sclera in the Seprafilm group (125.6 +/- 94.5 mmHg) was lower than that of the non-Seprafilm group (263.3 +/- 79.3 mmHg) (P = 0.0041, unpaired t test). A more prominent bleb was observed in the Seprafilm trabeculectomy group than in the non-Seprafilm trabeculectomy group. Histologically, the subconjunctival space was larger in the Seprafilm trabeculectomy group than in the non-Seprafilm trabeculectomy group. Mean IOP was significantly lower in the Seprafilm trabeculectomy group (9.9 +/- 0.6 mmHg) than in the non-Seprafilm trabeculectomy group (11.9 +/- 0.7 mmHg) 4 weeks after surgery (P = 0.0044, unpaired t test). CONCLUSIONS: Seprafilm can reduce postoperative conjunctiva-sclera adhesion and may be a desirable antifibrotic agent for trabeculectomy in the early stages of wound repair.

Intraocular use of hydrogel tissue adhesive in rabbit eyes.

PURPOSE: To evaluate the safety and efficacy of newly developed hydrogel glue to treat rhegmatogenous retinal detachments in in vitro and in vivo studies. METHODS: In the in vitro study, the solid hydrogel glue was soaked in a balanced salt solution (BSS). The pH was measured periodically, and the dissolution time was recorded. In the in vivo study in six albino rabbits, 0.1 ml of hydrogel glue was injected into the right vitreous cavity, and 0.1 ml BSS was injected into the left vitreous, as the control. Clinical, electroretinography (ERG) and histological examinations were performed. Retinal detachment with a retinal hole was created in 12 albino rabbits after vitrectomy. After fluid-air exchange, the hydrogel glue was applied to the hole in nine rabbits; three other rabbits were used as controls. Clinical and histological examinations were performed. RESULTS: The pH ranged from 6.65 to 8.14. The glue remained solid in BSS for 7 weeks. The glue injection did not induce inflammation. There was no significant difference between the study and control eyes in the ERG amplitude or the implicit times of the a and b waves. No significant histological abnormality was detected. The retina was reattached with glue in three of nine eyes. The histological examination showed glue under the retina. CONCLUSIONS: Hydrogel glue, which seemed to be minimally toxic to the eye, can be used to patch retinal breaks. However, methods to mix a small amount of each solution completely and a more effective intraocular delivery system for the glue are needed.

In vivo and in vitro feasibility studies of intraocular use of seprafilm to close retinal breaks in bovine and rabbit eyes.

PURPOSE: Seprafilm, a sodium hyaluronate/carboxymethylcellulose absorbable barrier developed to prevent adhesions after abdominal surgery, adheres well to wet tissue. The authors studied the efficacy of this film for sealing retinal breaks in animals. METHODS: In an in vitro study, a retinal detachment with a hole was created in bovine eyecups after the vitreous gel was removed. Seprafilm was placed over the retinal hole, and the strength of the retinal adhesion was measured by pulling the film. Permeability was tested by applying methylene blue to the film covering the retinal break. Seprafilm also was soaked in balanced salt solution (BSS) incubated at 37 degrees C, and the pH of the BSS containing Seprafilm was measured as it melted. In an in vivo study, Seprafilm was powdered and mixed in BSS solution, and 0.1 mL was injected into the right vitreous cavity in study rabbits. The same amount of BSS was injected into the right vitreous cavity in control rabbits. Ophthalmologic examinations were performed. Bilateral electroretinograms were recorded simultaneously before and 6 weeks after injection. Both eyes were enucleated for histologic evaluation. RESULTS: Seprafilm adhered well to the retina, was impermeable to methylene blue, and remained solid in BSS for 30 days before it dissolved, and its pH ranged from 7.2 to 8.0. No intraocular inflammatory reaction occurred after intravitreous injection of Seprafilm solution. There was no significant difference in amplitudes or implicit times of electroretinogram a-waves, b-waves, and oscillatory potentials before and after injection and between study and control groups. No significant retinal abnormality was detected by light microscopy in either group. CONCLUSIONS: The film adhered well to the retina with no signs of ocular toxicities. Further study is warranted for possible means of patching retinal breaks.