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ORIGINAL ARTICLES

Surgical Treatment for Normal Tension Glaucoma
T Yamamoto, Y Kitazawa
Department of Ophthalmology,
Gifu University School of Medicine,
Gifu-shi, Japan

Introduction

Normal tension glaucoma (normal pressure glaucoma; NTG) is the most prevalent subtype of glaucoma in Japan¹ and probably in other parts of Asia as well. Since there are no pathognomonic signs and symptoms for NTG, it is usually diagnosed by differentiating between diseases that mimic it. Table 1 shows the diagnostic criteria for NTG.

Table 1.Diagnostic criteria for normal tension glaucoma

While the pathogenetic mechanism of this chronic disorder is not yet certain, many believe that it is not a single disease but a group of diseases that have not yet been properly differentiated.^2-7 Based on a variety of possible pathogenetic mechanisms, several treatment modalities are being investigated, including ocular hypotensive therapy and various methods of improving ocular haemodynamics.

Abnormal intraocular pressure (IOP) is believed to play a role in the development of the optic neuropathy of NTG, as it does in primary open angle glaucoma (POAG). In cases of bilateral NTG, the eye with the highest IOP tends to have the most progressive visual field changes.⁸ There is no observable difference in the optic nerve head between NTG and POAG.⁹

Recent advances in surgery involving the use of antimetabolites have been successful in reducing IOP to approximately 10 mm Hg.^10-12 Moreover, the results of a multi-centered, collaborative study on the effect of surgical IOP reduction in NTG have recently been published.^13,14 Here, we discuss the findings from 2 studies conducted at our facility^15,16 and consider their implications regarding the surgical treatment of NTG.

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ORIGINAL ARTICLES

Surgical Management of Late Leaking Blebs
GC Sekhar
VST Centre for Glaucoma Care, LV Prasad Eye Institute,
Hyderabad, India

Six eyes of 6 patients who underwent surgical repair of leaking blebs following filtering surgery for glaucoma were retrospectively analysed. The conjunctiva could be mobilised in all cases with a fornix-based conjunctival flap, obviating the need for a graft. The scleral defect closure involved direct suturing in 2 patients, seleral rotational flap in 2, donor seleral patch graft in 1, and autologous fascia lata graft in 1. Only 1 patient required additional procedures to achieve closure of the leak. With a mean follow-up of 23 months (range 2 - 42 months), the intraocular pressure control was maintained in all except 1 patient. Adequate mobilisation of the conjunctiva and appropriate closure of the scleral defect are essential in the repair of leaking blebs.

Asian Journal of Ophthalmology 2000;2(1,2):10-13.

Key Words: Bleb leak; Fascia lata graft; Mitomycin-C; Scleral patch graft; Scleral rotational flap.

A Intraocular Lens Fixation in Infants and Small Children
A Vasavada, R Trivedi
Iladevi Cataract & IOL Research Centre &
Raghudeep Eye Clinic,
Ahmedabad, India

Congenital cataract remains a very important and difficult problem to manage. A number of studies have shown that congenital cataract continues to be a significant cause for children registered as partially sighted or blind. The surgeon plays an important, although small, role in its management. The entire team consisting of surgeon, parents, anaesthetist, paedi-atrician, intern, orthoptist, geneticist, and social worker have to prepare for long-term treatment.

From a clinical and surgical point of view, younger children pose special difficulties for the surgeon. Infants are more difficult to manage than toddlers (1-3 years) are, while children older than 5 years are relatively easier to manage.

A variety of measures are available to optically correct aphakia in children, including aphakic glasses, contact lenses and intraocular lenses (IOLs).¹ Although aphakic glasses can safely be used for bilateral cataracts and their power can be easily adjusted as the eye elongates, they are not always practical. Aphakic glasses are associated with the disadvantage of optical distortion and are not suitable for unilateral aphakia.

Likewise, contact lenses are safe and their power can be easily adjusted as the infantile eye elongates and they are acceptable for unilateral aphakia. However, they are associated with corneal complications. Long-term care, parents' non-compliance, and economic considerations also make contact lenses an impractical solution to aphakia for most children.

During the past 10 to 20 years, adult cataract surgery has advanced with improved surgical techniques, safer IOLs, and better quality viscoelastic material. These refinements have helped cataract surgeons to produce a technically safe eye for young children. Several recent reports show good results in the short to intermediate term after IOL implantation in paediatric eyes. However, long-term results are still awaited.^2-5

IOL implantation avoids many of the complications associated with contact lenses, but does carry its own risk. Surgeons may encounter increased inflammatory response due to implantation of an adult size IOL in small eyes. Although the literature has reported the incidence of posterior capsule opacification to be as high as 100%,⁶ recent advances in surgical techniques with the aid of primary anterior vitrectomy⁴ and improved IOL material help to ensure a quieter eye with clear visual axis. Under-correction is a reasonable proposition for managing rapid myopisation in infants and small children.⁷ In many parts of the world, aphakic glasses and contact lenses are impractical and IOL implantation remains the only realistic option.

In this article, we highlight some surgical tips that are useful for congenital cataract surgery (figures 1 and 2).

Figure 1. Congenital cataract in a child aged 11 months (nuclear and coralliform).

Figure 2. Congenital cataract in a child aged 4 Years (Lamellar Cataract)

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Trabeculectomy with Implantation of Silicon Rubber Slice for Neovascular Glaucoma
WZ Yang, FG Deng
Department of Ophthalmology, Guangzhou First Municipal People's Hospital, Guangzhou, China

The objective of this study was to observe the clinical effect of treatment for neovascular glaucoma of trabeculectomy combined with implantation of a silicon rubber slice. 28 patients (28 eyes) with neovascular glaucoma were treated by trabeculectomy combined with implantation of a piece of 3 to 5 mm silicon rubber, and the effect on intraocular pressure was observed. All patients were followed-up for 9 to 24 months (mean 18.3 months). The average intraocular pressure at the last visit was 21.65 mm Hg (range 17.30-28.97 mm Hg). The symptom of eye pain disappeared after surgery. Trabeculectomy with a piece of silicon rubber implantation is ideal therapy for neovascular glaucoma.

Asian J Ophthalmol 2000;2(1,2):18-20.

Key Words: Glaucoma; Trabeculectomy; Silicon rubber.