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December 2002
IN THIS ISSUE

Transcleral drugs overcome usual delivery limitations


Wavefront rated in 'top five' innovations of last 25 years

Ultrasound tool 'crystal ball' for anterior surgeons

Task force develops classification system for retinopathy screening

Cool laser blasts way to micro-incision cataract surgery

Anterior chamber maintainer adequate for micro surgery

Artemis 2 provides 'unprecedented' diagnostic readings

Laser biometry more reliable with experts and novices

In search of objective accommodation evaluation

Cataract surgery more than meets front of the eye

Combined surgery safe for PEX patients

Deferring PI in filtering surgery does not increase risks

Early glaucoma intervention delays progression

Oxygen may be the culprit in nuclear cataract

New IOL accommodates cataract patients

Trainee surgeons hold didactic wisdom

Antiviral treatment best defence for ocular herpes

Sutureless surgery advances with help of corneal glue

New weapons in the fight against corneal infection

New weapons in the fight against corneal infection

Intravitreal triamcinolone could reduce need for PDT re-treatment in eyes with exudative AMD

Ultra-thin lens reveals mystery accommodation

Two IOL styles prove to be equally accommodating in comparative trial

New drug improves diabetic retinopathy therapy

Good long-term results with combination surgery

Treating ocular cancer with designer molecules

Clear lens extraction prompts vitreoretinal concern

Roots of Fuchs' dystrophy may be found in mitochondrial genes

FEATURES
From The Editor
Reflections on Refractive Surgery
In Your Good Books
Bio-ophthalmology
Beyond The Eye
Regulatory Matters



Clear lens extraction prompts vitreoretinal concern

By Ana Hildago-Simón MD, PhD

NICE - Vitreoretinal surgeon Didier Ducournau MD voiced strong words of caution to anterior segment surgeons, particularly in relation to clear lens extraction, in a presentation at the XX ESCRS Congress.

Speaking at a clinical research symposium, the French specialist discussed the potential posterior segment complications of anterior segment surgery.
Dr Ducournau is the vice-president of the European Vitreoretinal Society (EVRS), an organisation created only two years ago. Its goal is to do for the posterior pole of the eye what the ESCRS is doing for the anterior segment.

"Our aim is educational. We embrace all the different philosophies and ways of thinking across Europe. Perhaps the main point of departure from the ESCRS is that we are more focused on the basic clinical findings and practical techniques related to the back of the eye, which are less well known than cataract operations," he said.

The love-hate relationship between anterior and posterior poles of the eye was the main theme of this year's EVRS conference. Some of the main topics discussed included techniques to deal with dislocated IOLs; combined phaco and posterior vitrectomy; choice of IOL; endophthalmitis; and pseudophakic retinal detachment. The rare anterior complications which can follow vitreoretinal surgery were also discussed.

Dr Ducournau reported that capsule ruptures during cataract surgery were a hot topic at the EVRS meeting. The patients should be referred to a posterior segment surgeon, after hermetically closing the cornea, he warned.

The first choice of the vitreoretinal surgeon would be to perform a complete posterior vitrectomy and a phacoemulsification aspiration, followed by lens implantation. A sulcus-supported IOL would be preferred but there was no clear favourite type of lens among participants at the Congress, he noted.

"Don't try to clean the anterior chamber with an anterior vitrectomy hand piece. They inject water into the vitreous cavity and effectively increase vitreous exit. To enlarge the incision is also a bad idea; posterior pole surgeons require a leakage free eye to work on.

"In fact, the situation most difficult to resolve in such a case would be a choroidal detachment caused by a hypotonia and increased by an inflammatory response. Finally, don't insert an IOL; it only makes things more difficult for the vitreoretinal surgeon who will have to deal with that eye later," Dr Ducournau explained.

He noted that for combined procedures, the vitreoretinal surgeon's preferred approach is to perform phacoemulsification through a 1.2 mm incision in order to have a self-sealing incision.
"Some of us like to work with the Open Phaco machine because it allows both vitrectomy with flow control and phacoemulsification through a small incision," he advised.

If the problem is a dislocated IOL, a complete pars plana vitrectomy is necessary. The aim is to leave the capsular bag as intact as possible. A new technique for removal of the displaced IOL was presented at the EVRS Congress in Greece.

It consists of getting hold of the distal haptic of the lens first, to take advantage of the haptic/body angles, then turning the lens and pulling it through the pupil without further damage to the eye structures.

A special forceps with a lever and a wheel is the recommended tool for this procedure.
Dr Ducournau also made some recommendations regarding the choice of IOL from the vitreoretinal point of view. Foldable IOLs to be inserted through a small incision are preferable.

In a survey of vitreoretinal surgeons present at the EVRS Congress, silicone was not chosen by any surgeons as a favourite lens material.
This is probably related to the condensation problems observed in silicone IOLs when injecting silicone, but also when injecting gas, he commented.

Long-term complications
Although it is true that most early post-cataract surgery complications are limited by phacoemulsification, the technique is not free of long-term complications, Dr Ducournau said.
He had particularly strong views on the practice of clear crystalline lens extraction followed by multifocal IOL implantation as a treatment for presbyopia.
"I strongly recommend you leave the natural lens in place unless extraction is truly required. You need to consider posterior eye complications and a severely increased risk of blindness for those patients," he cautioned.

Dr Ducournau explained that the rate of pseudophakic retinal detachment (PRD) has been stable in recent years, confirmed by some large studies.
Nonetheless, the general impression among anterior segment surgeons that the rate of PRD has decreased is simply not true, he said.

One reason for this misconception, Dr Ducournau believes, relates to narrow sub-specialisation of cataract surgeons which isolates them from posterior segment problems. He noted that most cataract surgeons only see a small percentage of the PRD cases when they occur.
The second reason is the mean onset delay of four years and seven months which is longer than previously thought.

With the increase in life expectancy of the population, this delay has major implications but not necessarily for the surgeon who performed the cataract operation.
He stressed that although the severity of retinal detachments (RD) has not changed with the introduction of phacoemulsification, the rate of failure of RD is clearly increased by capsulotomies.

The risk is doubled if Nd:YAG is performed within six months after cataract extraction, and tripled if a capsulotomy is performed within six months and RD also occurs within the first six thereafter.
"The faster the retinal detachment occurs after phacoemulsification or Yag, the higher the failure risk and the effects are cumulative," he emphasised.

For more information on the European Vitroretinal Society, visit its web page at www.evrs.org


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