We had tested the lock several times on the first case and had experienced no difficulty. When the difficulty did arise, it left me in a very dangerous situation. I subsequently purposely destroyed the locking mechanism of the forceps .

David B. Davis II, M.D. Hayward, CA

Storz replies: Storz Instrument Company was certainly con­

cerned to read of the difficulty Dr. Davis experienced with the Park intraocular lens holder he purchased from us. We inspect all of our instruments prior to their leaving our plant, and it is obvious that this product was in working condition when it arrived, since Dr. Davis stated that he "tested the lock several times on the first case and experienced no difficulty."

We received no product complaint from Dr. Davis and it is unfortunate that the locking mech­anism on the forceps was purposely destroyed. Since the instrument was not returned to us, we cannot presume to know what could have caused the pro­duct to fail between cases.

Steve Stephens Vice President, Product Management

IRIS A TROPHY

To the Editor: Sphincter erosion and iris atrophy in the vicinity

of the loop pegs do occur with Supramid (nylon 6) and Prolene (polypropylene)-looped lenses, although not nearly as frequently as with metal-looped lenses.

It appears to me that Prolene is somewhat rougher than Supramid and the only reason to expect sphincter damage is wi th the prolonged use of rather strong miotics. If this is avoided, and the general practice now is to avoid miotics with intraocular lenses, then the problem should be infrequent and rather mild.

Henry Hirschman, M.D. Long Beach, CA

POSTERIOR CHAMBER LENS

To the Editor: Following is a brief summary of the new Boberg­

Ans posterior chamber implant, manufactured by Rayner. This is only a preliminary report since I feel that any presentation of clinical results would be

premature prior to completion of an IS-month ob­servation period.

The posterior chamber Boberg-Ans lens re­sembles a Binkhorst 4-loop lens except that the optic is positioned behind the pupil (Fig. 1,2). The poste­rior haptic is a continuation of the optic and is slightly longer than the corresponding anterior loops (Fig. 3). The posterior haptic is angled ten degrees posteriorly and is perforated at each end to

reduce lens weight (Table I).

Fig. I (Boberg-Ans) . Anterior view of the Binkhorst 4-loop lens (Idl ) and the Boberg·Ans lens (right).

Fig. 2 (Boberg-Ans) . Side view of the Boberg-Ans lens (top) and the Binkhorst lens (bollom).

The smooth solid posterior haptic acts as a glide and protector for the vitreous while the lens is intro­duced through the pupil. The anterior loops are made slightly shorter to engage the pupillary margin

148 AM INTRA-OCULAR IMPLANT SOC J-VOL. V, APRIL 1979

and slide onto the front of the iris. The lens rests in the posterior chamber, kept in place by its anterior clip-like loops which are unlikely to cause any cor­neal damage during lens introduction. It is easy to manipulate the upper pupillary edge between the haptics.

Fig. 3 (Boberg-Ans). Posterior view of the Boberg-Ans lens.

The power of this lens is 21.00 diopters, cor­responding to a 19.00-diopter lens in front of the pupillary plane and 11.00 diopters of spectacle cor­rection. So far, I have used this len§ in eleven cases and have found it easy to insert with less chance of damage to the corneal endothelium, less reaction from the iris and less chance of pupillary block. It is suitable for use with both intracapsular and extra­capsular cataract extraction.

Independently and at nearly the same time, Eric Arnott designed a very similar posterior chamber lens (also manufactured by Rayner), putting the anterior loops at right angles to the posterior haptic. This lens has the same advantages as the Boberg-Ans lens, but the cross shape demands more skill to insert. I find that the Boberg-Ans lens has perhaps greater stability in the eye.

10rn Boberg-Ans Charlottenlund, Denmark

Table 1. Descriptive data for the Binkhorst and Boberg-Ans lenses.

Weight in aqueous (mg)

Weight in air (mg)

Posterior length (mm)

Anterior length (mm)

Diameter of optic (mm)

Center thickness of optic (mm) (varies with power)

Diagonal pupil size (mm)

Minimum pupil size (mm2)

Posterior angulation of anterior loops

Distance between nylon support elements (mm)

Posterior haptic thickness (mm)

Anterior loop thickness (mm)

Binkhorst 4-loop Lens

1.8

14.3

8.5

7.5

5.0

0.5

2.8

2.0

10°

2.0

0.2

0.12

AIOIS Scientific Sessions

Boberg-Ans Posterior

Chamber Lens

1.2

9.8

9.0

7.5

4.0

0.5

2.8

2.0

10°

2.0

0.2

0.2

Century Plaza Hotel, Los Angeles

March 25-29, 1980 March 24-28, 1981 April 20-24, 1982 April 5-9, 1983 April 3-7, 1984

April 9-13, 1985

AM INTRA-OCULAR IMPLANT SOC J-VOL. V, APRIL 1979 149