Year : 1967 | Volume
: 15 | Issue : 2 | Page : 67--68
Improved stenopic slit for finding the optimal site for optical iridectomy
Daljit Singh, KK Khanna
Department of Ophthalmology, Medical College, Amritsar, India
Department of Ophthalmology, Medical College, Amritsar
|How to cite this article:|
Singh D, Khanna K K. Improved stenopic slit for finding the optimal site for optical iridectomy.Indian J Ophthalmol 1967;15:67-68
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Singh D, Khanna K K. Improved stenopic slit for finding the optimal site for optical iridectomy. Indian J Ophthalmol [serial online] 1967 [cited 2023 Mar 27 ];15:67-68
Available from: https://journals.lww.com/ijo/pages/default.aspx/text.asp?1967/15/2/67/38683
The stenopic slit found in all the trial sets is 1-2 mm by 15-35 mm in size. It splits an opaque disc into two halves. [Figure 1]. It is useful in finding out the axis of the cylinder.
The same stenopic slit is used in cases of corneal opacities to find out the optimal site for optical iridectomy. After dilating the pupil with a mydriatic, the slit is rotated in front of the eye and the axis which gives maximum clarity is chosen for optical iridectomy. This simple subjective test fairs well in a large percentage of cases.
In a good number of cases however, the test is beset with difficulties. The patient is not confident in pin-pointing the best position of stenopic slit. Sometimes he gets blurring of vision and diplopia even in the best axis. The reasons for blurring and diplopia are explained as follows. When the pupil is dilated with a mydriatic and a stenopic slit placed in position, the eye has for practical purposes two pupils, one on either side of the opacity. If there is a sufficient error of refraction the patient gets diplopia or sees the words on the test chart blurred.
Although with the help of the available stenopic slit, we get the direction in which an optical iridectomy will give the best results, in certain cases it becomes really difficult to choose between the two ends of the stenopic slit. The iridectomy can be done only at one end.
The difficult situation has been remedied by the use of a slit which at one time uncovers the pupil only on one side of the opacity. The patient does not get diplopia and he sees better. In problem cases the surgeon has no difficulty in deciding for the site of optical iridectomy.
The stenopic slit is easily made as follows. A plane glass having a size appropriate for the trial frame is selected. In the middle of it a black circle 12 mm in diameter is painted. In an area 1 mm by 6 mm or 2 mm by 6 mm, starting from the centre and extending to margin of the circle, the paint is rubbed off. A thin dark line is drawn from the stenopic slit thus formed to the edge of the glass disc. This line helps in correctly reading the axis of the slit. [Figure 2].
To use the slit, it is placed in front of the eye in such a way that the black circle hides the cornea of the patient, thus bringing the stenopic slit in the desired position, i.e. any one radius of the cornea. The slit is rotated and the best axis found as usual.
An improved stenopic slit is presented. The difficulties with the ordinary stenopic slits provided in the trial sets are discussed and their eradication with the new stenopic slit explained.