DR.VENKATAPRABHAKAR GUDURU

Dr.Jagadeesh Kumar Reddy K

Abstract

Purpose:To design and evaluate a new intraocular lens to prevent negative dysphotopsia in the form temporal crescentric shadow post cataract surgery

Methods:Most accepted theory being gap between iris and optic leading to a grey shaded area formed between ray missing IOL and ray refracted by IOL causing a temporal crescentric shadow.our concept was to give normal crystalline lens profile to IOL optic to eliminate gap between IOL and iris which simulates reverse optic capture or better.The new IOL is of hyperbola shape where optic comes in contact with pupil margin after implantation in the capsular bag there by eliminating the space that light rays can pass through and produce negative dysphotopsia.The lens was implanted in 56 patients in whom the other operated eye had negative dysphotopsia.

Result:None of the 56 patients(at 1 year) complained of any dysphotopsia in which ADL lens was implanted.This study suggests that new IOL design is effective in eliminating negative dysphotopsia

Anti Dysphotopsia Lens (ADL) – A novel intraocular lens design to prevent dysphotopsia post cataract surgery.

Prabhakar G V, J K Reddy

 

Full Text

1) Purpose:

To design and evaluate a new intraocular lens to prevent negative dysphotopsia in the form of a temporal crescentic shadow post cataract surgery.

2) Methods:

Most accepted theory of dysphotopsia is the presence of a gap between iris and optic which leads to a grey shaded area formed between the ray missing IOL and the ray refracted by IOL, causing a temporal crescentic shadow. Our concept was to give a normal crystalline lens profile to IOL optic by eliminating the gap between IOL and iris which simulates reverse optic capture or better.The new IOL is of hyperbola shape where optic comes in contact with pupil margin after implantation in the capsular bag thereby eliminating the space that light rays can pass through and produce negative dysphotopsia.The lens was implanted in 56 patients in whom the other operated eye had negative dysphotopsia.

3) Results:

None of the 56 patients (at 1 year) complained of any dysphotopsia in which ADL lens was implanted.

4) Conclusions:

This study suggests that new IOL design is effective in eliminating negative dysphotopsia

Introduction:

Unwanted optical phenomena such as negative and positive dysphotopsias are well known side effects after cataract surgery (1). Negative dysphotopsia is defined as the perception of a shadow obscuring the temporal field of vision, while positive dysphotopsia is characterised by halos, arcs or streaks around point light sources (2,3).

In the majority of cases, dysphotopsias resolve or diminish over time. Therefore, waiting and reassurance are reasonable initial treatment strategies. However, in 0.2 to 1 % of pseudophakic patients, severe symptoms will persist (2,4) and additional surgery may be required.

Our idea was to design a new intraocular lens eliminating the factors causing dysphotopsia. Most accepted theory of dysphotopsia is the presence of a gap between iris and optic which leads to a grey shaded area formed between the ray missing IOL and the ray refracted by IOL, causing a temporal crescentic shadow.

Our concept was to give a normal crystalline lens profile to the IOL optic, to eliminate gap between IOL and iris which simulates reverse optic capture or better. The new design IOL is hyperbola shape, like a contact lens, with no junction between the optic and haptic with convexity facing anteriorly (fig 1-4) The optic comes in contact with pupil margin after implantation in the capsular bag there by eliminating the space that light rays can pass through and produce negative dysphotopsia.

Methods:

All patients underwent uneventful phacoemulsification with our IOL implantation in the capsular bag. Complaints of dysphotopsia were noted before surgery and at each follow- up visit. Evaluation included uncorrected (UDVA) and corrected (CDVA) distance visual acuity, manifest refraction, Goldman applanation tonometry, slit-lamp examination, Scheimpflug photography (Pentacam, Oculus Optikgeräte GmbH, Wetzlar, Germany) and Anterior segment optical coherence tomography (Cirrus, Carl Zeiss Meditec, Inc, Dublin, CA).

Informed consent was obtained from all the participants. Study protocols adhered to the declaration of Helsinki and was conducted after getting approval from the ethical committee.

Fig 1: Showing ADL lens with central optic and 360 degrees continuous haptic angulated posteriorly and two dialling holes.

Fig 2: showing ADL lens postoperatively highlighting the proximity between optic and rhexis margin

Fig 3: showing normal crystalline lens profile of capsular bag after ADL lens implantation.

Fig 4: OCT image

 

showing that there is no gap between optic and iris, thus eliminating the gap for rays to pass through.

Fig 5: graph highlighting the results showing that none of the patients experienced negative dysphotopsia post ADL lens implantation.

Discussion

The current treatment options for severe persistent negative dysphotopsia include IOL exchange with placement of a secondary IOL in the bag or in the ciliary sulcus, implantation of a supplementary IOL, reverse optic capture and Nd: YAG anterior capsulectomy. However, in some cases the symptoms may persist after treatment (2, 4-12). We have shown that implantation of our ADL lens can successfully treat negative dysphotopsia. Negative dysphotopsia occurs with IOLs of different materials (2,5,10,11) with both rounded and squared edges (2,10,13). Some patients might develop a unique interaction between the optical pathways of the eye and the IOL (4). One possible mechanism is the reflection of light rays between the IOL edges and the anterior capsulorhexis, which can be successfully treated with reverse optic capture.

A large distance between the anterior surface of the IOL and the posterior iris surface also play a role (3,14). The reduction of this distance is achieved by implantation of ADL lens and hence negative dysphotopsia was avoided in all cases.

Results:

ADL lens was implanted in 56 patients with negative dysphotopsia in the other eye (fig 5). The mean age of the patients was 63.0 ±6.6 years. None of the patients experienced negative dysphotopsia post-surgery.

None of the patients had pupillary block, IOP rise or pigmentary dispersion.

Conclusion:

Implantation of the ADL lens is a safe and effective treatment of negative dysphotopsia. ADL lens eliminates the gap between optic and pupil. Thus, there is no space for rays to pass through thereby eliminating the chances of dysphotopsia.

References

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