Year : 1981 | Volume
: 29 | Issue : 3 | Page : 215--216
The myth fyodrov surgery
Department of Ophthalmology M.A.M. College, New Delhi, India
L D Sota
Department of Ophthalmology M.A.M. College, New Delhi
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Sota L D. The myth fyodrov surgery.Indian J Ophthalmol 1981;29:215-216
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Sota L D. The myth fyodrov surgery. Indian J Ophthalmol [serial online] 1981 [cited 2024 Feb 27 ];29:215-216
Available from: https://journals.lww.com/ijo/pages/default.aspx/text.asp?1981/29/3/215/30885
Surgical correction of myopia has been attempted by doing Keratoplasty, Lens extrac�tion, scleral excision and Keratomileusis. Recently correction of myopia by surgical means by 'Fyodrov' has created lot of interest and confusion not only among ophthalmolo�gists but also in lay public because of extensive press coverage given.
Fyodrov surgical correction and the modi�fication introduced comprises of giving partial thickness central corneal trephine of 3-4 mm and peripheral radial incision going upto limbus numbering from 8-12 in number. It is claimed that within 24 hours patient can see 6/6 or 6/9 without the aid of any glass. The present study is undertaken to explain partially the mechanism of the immediate improvement in vision.
The study is based on the simple principle of pin-hole camera. In pin hole camera the image formed is free from distortion and depth of focus is great, but disadvantage is that degree of sharpness produced is never of very high order because if the diameter of the hole is reduced beyond a certain limit the illumina�tion gets very low. Also one has to understand the formation of blur circle. The distribution of the light on the retina itself will be circular and is called blur circle. For a given distance blur circle is directly proportional to the diameter of the pupil. Additional factor is closer the pin-hole to the eye, the better is the vision. That is why in the present study con�tact lens with central aperature is used to find the degree of improvement in vision.
MATERIALS AND METHODS
Myopia in the rage of -2.5 D to -9 D was taken and the study was divided into 4 groups depending upon the response. Astigmatic correction was not taken into account.
Group I - 2.5 D to - 3.5 D
Group II - 3.75 D to 5 D
Group III - 5.25D to - 7.5 D
Group IV - 7.75 D to - 9.0 D
Their visual acquity with glasses, with pin-hole of 2 mm in the trial frame and black contact lense with 2 mm central aperature was studied. Also was used transparent plain con�tact with 2mm central aperature and contact lense with 0.75 lmm and 1.5mm central apera�ture.
OBSERVATIONS AND DISCUSSION
Pin-hole of 0.7 mm, Imm and 1.5 mnm were not effective as the patient found difficult to look into it. Patient had to turn his head to focus the object and the clarity was not good. It is observed that with contact lens having a central aperature of 2 mm, it was possible to improve the vision upto 6/ 18-6/12 in the higher range of myopia. While normal vision or near normal vision was improved in the rest of the cases. It is obivious that closer the aperature to the cornea the better is the vision. I presume in Fyodrov surgery viewing area of the cornea through which the light passes is re�duced to 2-2.5 mm when the central corneal trephine is used because of oedema and that is how the vision improves immediately post�operatively. Also, it is postulated that perma�nent improvement in vision which is claimed is partly because of reduction of the area on the cornea through which the light passes.
With transparent piano contact lens of central aperature of 2 mm when applied to the same group of patient it was found that patient experience better quality of vision and in some cases patients were able to read few words more. That shows that with transparent con�tact lens the quality of vision was better as compared to black contact lens of the same central aperature Transparent contact lens nearly simulate the cornea and total illumina�tion was better.