Half of world blindness related to unoperated cataracts

May 1, 2006

With the world's population getting older and the rate of blindness increasing, cataract surgeons worldwide are facing some clinical challenges in the years ahead, according to Stephen A. Obstbaum, MD, of the United States.

With the world's population getting older and the rate of blindness increasing, cataract surgeons worldwide are facing some clinical challenges in the years ahead, according to Stephen A. Obstbaum, MD, of the United States.

Obstbaum was unable to attend the World Ophthalmology Congress and so Emanuel Rosen, MD, of the University of Manchester, UK, presented his paper on his behalf outlining the challenges that cataract surgeons need to address if world blindness is to be controlled.

According to the report, 45 million people worldwide are blind and a further 135 million people reportedly have some form of vision disability. Worryingly, world blindness is expected to increase at a rate of 2 million per year as the world's population ages. Today, half of the world's blindness is related to unoperated cataracts.

With the World Health Organization's 20/20 initiative for the right to sight, the global initiative gives direction for blindness prevention that helps raise some indicators for disease control, human resource development, and providing infrastructure and technology. "Cataract surgery is an integral proponent of that initiative," Rosen said.

Delivery of care will be based on structure; physical and organizational properties of a setting where quality eye care is provided. Rosen outlined the structural indicators, which include surgical environment, education and training for physicians, medical care and equipment, and anaesthesia personnel. Process indicators include diagnosis, patient education, informed consent and appropriate indicators for surgery. Outcome indicators include visual acuity, adverse events, glare and contrast sensitivity, visual rehabilitation, refractive stability and patient satisfaction.

The goals for cataract surgery are to improve visual acuity, to improve functional vision and to improve quality of life.

Rosen listed six global challenges for the cataract surgical community; to deal with a backlog of patients with cataract blindness; to deal with the increasing number of patients with cataracts in the aging population; to standardize the approach to structure and process for managing cataract patients in global regions; to strengthen efforts for adequate follow-up; to put in place systematic data collection and finally to recognize that outcomes data are essential to the formulation of standards and approaches for the management of cataract patients.

IOP: hit the target

A target intraocular pressure (IOP) should be set whenever the diagnosis of ocular hypertension or glaucoma is first made, and it should be re-evaluated at each follow-up visit as part of the assessment of the efficacy of treatment for stopping visual field progression and protecting the optic nerve, said Curt Hartleben, MD, from the Institute of Ophthalmology, Mexico City, Mexico.

Hartleben talked about the factors that should be taken into account in determining a target IOP. Disease and disease severity are two primary considerations and, in that regard, there is some guidance provided by the results of the large randomized, clinical trials. For ocular hypertensives, the target might be based on achieving a 20% to 35% reduction from baseline IOP, while a more aggressive goal of a 30% to 35% reduction or to at least between 15 and 18 mmHg should be aimed for in individuals with mild initial primary open angle glaucoma (POAG).

In eyes with advanced POAG or normal tension glaucoma, available evidence suggests an even lower IOP range of 11 to 13 mmHg should be the goal, while in eyes with normal tension glaucoma having very excavated optic nerves, a target of 8 to 10 mmHg is recommended. "Remember, glaucoma is an optic nerve neuropathy and the target should be lowered for eyes with more damage," said Hartleben.

Another factor to consider is the age of onset based on its relationship with life expectancy. In that regard, Hartleben noted older patients may need a less aggressive IOP target than their younger counterparts.

Finally, quality of life should never be overlooked. "The more medications the patient is on, the greater the reduction in quality of life and compliance," he concluded.

Making PKP successful

Careful planning of penetrating keratoplasty (PKP) surgery is essential to its success, according to Mark Mannis, MD, US, when he outlined four key elements to a successful PKP surgery. The first is careful patient selection, the second careful donor selection, third proper preoperative planning and last a readiness for the unexpected.

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