Endoscopic goniotomy with the free electron laser in congenital glaucoma rabbits

Endoscopic goniotomy: early clinical experience in congenital glaucoma

PURPOSE

To review the technique and early outcomes of endoscopic goniotomy (EG) in children with opaque corneas and primary congenital glaucoma (PCG) or developmental glaucoma with ocular or systemic anomalies (DG).

METHODS

EG was performed for approximately 300 degrees of the angle through temporal and superonasal corneal incisions. We retrospectively reviewed consecutive cases from 2003 to 2007. Primary outcome was intraocular pressure (IOP) change from baseline to last postoperative visit. Success was defined as IOP < or=21 mm Hg with or without medication but no further surgical intervention.

RESULTS

Fourteen eyes of 8 patients (4 PCG, 4 DG) were included. Mean age at surgery was 3.88+/-3.72 months. The reduction in IOP from baseline to the last follow-up visit was -16.7+/-16.7 mm Hg. Success was achieved in 6 of the 16 eyes (Total=43%, PCG=50%, DG=30%). Corneal diameter and axial length remained stable in all eyes. Two patients with DG needed additional surgery after 8 to 9 months. Complications included cataract and zonular dialysis both in 2 patients with aniridia.

CONCLUSIONS

This pilot study indicates that EG shows reasonable potential for IOP control in congenital glaucoma. The safety and efficacy of EG needs to be further studied with a larger sample size and comparison to other angle surgery techniques.

Endoscopic free electron laser technique development for minimally invasive optic nerve sheath fenestration

PURPOSE

This study proposed to develop a technique for efficiently accessing the posterior orbital space using endoscopy and attempted application of free electron laser (FEL) energy, biopsy forceps, electrocautery, and CO(2) insufflation to posterior orbital tissues.

METHODS

Through an inferior transconjunctival incision, access to the posterior orbital space was attempted in 14 eyes of 7 non-survival pigs. FEL energy (6.1 microm, 30 Hz, delivered via 250 microm hollow-glass waveguide), biopsy forceps, and monopolar electrocautery application were endoscopically attempted in the posterior orbit. CO(2) gas insufflation effects were assessed by analyzing arterial blood gases at 30-minute intervals for 1.5 hours.

RESULTS

The posterior orbit was accessed in 13 of 14 eyes, the optic nerve was encountered, and FEL energy was applied in 8 of 14 eyes. Use of biopsy forceps and electrocautery were successful. Although ANOVA results for arterial blood gas changes were not statistically significant, visibility was adequate without CO(2) insufflation.

CONCLUSIONS

The posterior orbit was endoscopically accessed and the optic nerve was exposed and successfully treated with FEL energy. CO(2) insufflation did not alter blood gases, but did not further enhance visibility in this study.

A case of primary congenital glaucoma: a diagnostic dilemma

BACKGROUND

Primary congenital glaucoma generally presents with a classic clinical triad of photophobia, blepharospasm, and epiphora caused by the corneal changes that occur secondary to increased intraocular pressure (IOP). The condition typically presents bilaterally and is rarely hereditary. Onset is from age 2 months to 2 to 3 years.

CASE REPORT

A 2-year, 5-month-old Hispanic boy presented with an enlarged right eye and an intermittent right exotropia, without tearing or photophobia. Examination also found high myopia and an optic nerve cup-to-disc ratio larger in the right than the left eye. Referral to a pediatric ophthalmologist was initiated. On the first examination under anesthesia (EUA), the child was diagnosed with unilateral megalocornea with a normal IOP. He did not have any other typical signs and symptoms of primary congenital glaucoma. An EUA 8 months later led to a diagnosis of primary congenital glaucoma based on the new appearance of Haab's striae, further enlargement of the cornea, and an elevated IOP. At this point, medical management was instituted.

CONCLUSION

This case shows the importance of recognizing signs of primary congenital glaucoma so that appropriate management can begin as soon as possible to provide the best visual outcome for a child.

Optic nerve sheath fenestration with endoscopic accessory instruments versus the free electron laser (FEL)

BACKGROUND AND OBJECTIVE

The free electron laser (FEL) can efficiently produce an optic nerve sheath fenestration using an endoscopic approach. To develop a surgical protocol, this study compared effectiveness of available accessory endoscopic instruments to endoscopic FEL delivery effectiveness in producing optic nerve sheath fenestrations.

STUDY DESIGN/MATERIALS AND METHODS

An endoscope was used to perform optic nerve sheath fenestrations on goat optic nerves. Accessory endoscopic instruments and glass-hollow waveguides (250 and 320 microm in diameter) were inserted into the instrument channel for comparison. FEL energy (6.45 microm, 30 Hz) was delivered to the tissue through the waveguides and histological analysis was performed.

RESULTS

The endoscopic instruments alone were unable to incise the optic nerve sheath. The FEL successfully incised the sheath and the biopsy forceps extricated the circular flap.

CONCLUSIONS

Endoscopic optic nerve sheath fenestration using FEL energy followed by biopsy forceps for sheath extrication produced good results, thereby creating a feasible protocol for optic nerve sheath fenestration.

In vivo optical imaging of expression of vascular endothelial growth factor following laser incision in skin

BACKGROUND AND OBJECTIVE

Laser-tissue interaction studies have focused on laser-induced secondary effects on tissue and the postmortem histological analysis of laser wounds. In this study we addressed wound healing and possible impairment of wound healing due to collateral tissue damage by in vivo imaging of gene expression.

STUDY DESIGN/MATERIALS AND METHODS

We used a transgenic mouse model containing a VEGF promoter driving a GFP reporter gene to image VEGF expression in vivo. Twenty-two mice received two full thickness incisions in the dorsal skin: one with the Free Electron Laser (lambda = 6.45 microm, 52.9 mJ/mm(2)) and one with a scalpel. Mice were imaged for GFP expression at 3 days, 1, 2, 3, and 4 weeks. Confocal microscopic imaging was performed at 2 weeks.

RESULTS

Peak GFP expression was seen at 2-3 weeks and was localized in fibroblasts. FEL lesions showed more total GFP expression than scalpel lesions but this was only statistically significant (P < 0.05) at 2 and 4 weeks. The full-width half-max (FWHM) of the GFP expression was always larger for the FEL lesion compared to the scalpel lesion but was only statistically significant (P < 0.05) at 2 and 3 weeks. At 2 weeks the extent of the GFP expression in the laser lesion was on average 55 microm beyond that seen in the scalpel lesion but correlated with the number of laser passes.

CONCLUSIONS

Feasibility of using transgenic mice carrying photoactive reporter genes for studying cellular process of laser-inflicted wound repair in a noninvasive, in vivo manner was shown. GFP expression mediated by the VEGF promoter in fibroblast showed minimal impairment of wound healing due to the laser.