Eye (1989) 3, 663--671 Radial Keratotomy: 500 Consecutive Cases W. J. JORY London Summary A report on 500 consecutive eyes having radial keratotomy for myopia and myopic astigmatism is presented. Surgery was on an out-patient basis under local ana­ esthetic, with a foUow-up of 99.2 % of cases, 91.8% of the 294 patients elected to have radial keratotomy on the fellow eye. The surgical protocol was designed to minimise side effects and complications rather than maximise the reduction in myopia. 6/12 unaided vision or better was achieved by 99% of cases in the low myopia group, 91 % in the middle and 41 % in the high myopia group. Persistent hypermetropia of +1.oon or greater occurred in only 0.4% of cases and secondary astigmatism of 1.oon or greater in 1 % of cases. Corneal perforations were minimised by single-pass incisions, but this was at the cost of lesser myopic corrections in the higher myopic group. Centering on the visual axis rather than the centre of the pupil minimised glare sensitivity. No patient developed potentially blinding complications. Selection of Patients likely visual and dioptric results of the Patients were selected on the following surgery. criteria: (10) Although many patients were seen (1) Lower age limit was 18 years, there was no direct, they were encouraged to visit their upper limit for the surgery. general practitioner before attending the (2) The refractionwas stable. centre. Consultation reports were sent to (3) There was no active external ocular general practitioners before treatment disease. together with an account of radial kerato­ (4) Physiological myopia was present without tomy, and an operation report on the day of the ophthalmoscopic signs of progressive surgery. A finalreport was sent on completion pathological myopia. of treatment. (5) Candidates were either intolerant of con­ Technique of radial keratotomy tact lenses or required reduction or abolition (1) All surgeries were done on an out-patient of their refractive error for occupational basis in a sterile operating theatre and using reasons or because of sporting activities. sterile surgical techniques. (6) Amblyopic eyes were accepted. (2) Surgery was done using an operating (7) Patients were informed of the advantages microscope. and disadvantages of radial keratotomy. (3) Pre-medication of 10 mg valium was given (8) Patients were counselled on the possible orally. side effects and complications of radial (4) Surgery was done on the non-dominant keratotomy. eye first followed by the fellow eye approxi­ (9) Patients were given an estimate of the mately six weeks later. Correspondence to: London Centre for Refractive Surgery, 21 Devonshire Place, London WIN IPD. 664 W. J. JORY (5) The amount of surgery was planned by radial and transverse keratotomy. Secondary nomogram based on patient's age and refrac­ surgery was performed on 54 eyes or 10.8% of tive error. the total (PERK 9%). The total number of (6) Ultrasonic pachymetry to determine cor­ patients treated was 294, of which: 194 (66%) neal thickness was performed immediately were males (PERK 52%) and 100 (34%) preoperatively. females (PERK 48%). Follow up was possible (7) The eye was anaesthetised with Guttae in 496 out of the 500 cases (99.2%). Maximum Amethocaine 1% . follow-up was two years. Out of 294 patients, (8) The eye was kept minimally moist with 270 (91.8%) elected to have radial kerato­ sterile normal saline during the surgical tomy on the fellow eye. (Some of these cases procedure. are not included in the 500 consecutive ker­ (9) Great care was taken to mark the intersec­ atotomies described here). Seven patients tion of the visual axis on the cornea. had planned uniocular surgery. At baseline (10) Oull marking trephines with cross hairs the spherical equivalent refraction was (i) and 3.00, 3.25, 3.50, 3.75, 4.00, 4.50, 5.00 and -1.000 to -3.000 in 127 eyes (plus two not 6.00 mm diameters were used. followed up and therefore excluded). Eighty (11) Radial incisions were done with a single­ nine of these had radial keratotomy and 38 edged 45° angle diamond blade set at 115% of had radial and transverse keratotomy. (ii) the average para-central corneal depth -3.250 to -6.00D in 211 eyes with 153 measured by ultra-sonic pachmetry, aiming to patients having radial keratotomy and 58 achieve between 90% and 95% depth at the having radial and transverse keratotomy. (iii) commencement of the radial inCisions. Inci­ -6.250 to -9.000 in 117 eyes (plus two eyes sions were centrifugal, i. e. from optical zone not followed up and therefore excluded). One to periphery. The ultrasonic probe was placed hundred and one cases had radial keratotomy exactly on the optical (clear) zone mark in the and 16 had radial and tranverse keratotomy. position of the radial incisions. (iv) over -9.000 in 45 eyes. (12) Transverse incisions were done with a Some of the reasons given for wanting ker­ double-edged diamond blade. atotomy surgery included: (i) intolerance of (13) �iamond blades were set in micrometer contact lenses. handles and calibrated with a blade guage. (ii) Fear of losing glasses or contact lenses in (14) Both eyes of the same patient were done an emergency. with the same blade. (iii) Thickness and weight of glasses. (15) Incisions were thoroughly irrigated with (iv) Inability to participate in outdoor activi­ normal saline at the conclusion of the surgery. ties particularly swimming but also other (16) Guttae Gentamycin and Guttae Cyclogyl sports i.e. mountaineering and skiing. 1% were instilled in the operated eyes. (v) Improvement of unaided visual acuity to (17) The eye was lightly patched for three meet occupational requirements. hours only. (vi) No surgery was done for cosmetic reasons (18) Post-operative pain was controlled with only. tablets OF118 for 12 to 18 hours only. (19) Guttae Maxitrol was instilled post-oper­ Visual results atively twice a day for two weeks. The visual results are expressed as a percent­ (20) Follow-up was at two weeks and again at age of 6/12 uncorrected visual acuity since it is the two weeks after the second operation and considered that this is the most meaningful requested at six months and one year. No statistic to present to the patient considering patients have been discharged from care. radial keratotomy surgery. Average predicted The standard interval between eyes having result or average dioptric result gives a less surgery was six weeks, and between primary meaningful forecast to the patient. The per­ and secondary surgery on the same eye was centage of patients achieving emmetropia is between three and six months. not used, since for reasons described later, it is Study Population not always desirable to aim for this. Success of Five hundred consecutive eyes had radial or the surgery as defined by the International RADIAL KERATOTOMY: 500 CONSECUTIVE CASES 665 Society of Refractive Keratoplasty is 6/12 (20/ (2) Persistent signs and symptoms that did not 40) unaided vision.: reduce best corrected visual acuity. In the low myopia group of -1.000 to (3) Complications that actually or potentially -3.000, 125 eyes out of 127 achieved 6/12 reduced visual acuity. unaided vision or better. Of the remaining two cases, one had 4 cylinder pre-operatively (1) Transient Signs and Symptoms and one case was amblyopic. Ocular pain often described as similar to In the group of moderate myopia of toothache in the eye was common but was -3.250 to -6.000, 211 eyes had surgery. usually controlled by oral analgesics such as One hundred and eighty-six out of the 211 OF118. Pain was nearly always better by the eyes achieved 6/12 vision unaided or better. following day and was eased on the day of sur­ In the high myopia group of -6.250 to gery by removal of the eye patch. Many -9.000, 117 eyes had surgery, forty-five of patients described a slightly scratched feeling these achieved 6/12 vision or better unaided in the eye for two weeks post surgery after following surgery. which it gradually subsided. Pain was usually In the very high myopia group of greater more severe when an increased number of than -9.000 45 eyes had surgery. Every eye incisions had been made or where the corneal achieved a significant and major reduction in epithelium had tended to strip off during the the myopic spherical equivalent. incision. Very little conjunctival injection was Most refractions were stable at between caused by this surgery. one and two months and 5% of cases con­ Fluctuation of vision more properly tinued to decay up to the sixth month gate and described as variation of refraction, was three eyes to the one year gate. reported by many patients especially during The surgical plan was slightly conservative the first month but this decreased steadily. in the surgery on the first eye and used the (Table III) The eye became more myopic experience of the response of that eye in plan­ during the day but only one patient has ning the operation on the second eye. Thus required two pairs of glasses (for day and most of the secondary surgery was done on evening wear). Variation of refraction prob­ the firsteye. It was found that the response of ably occurs in all cases but is often not appar­ the second eye could be predicted accurately ent to the patient. It is caused by the increased from the response of the first eye. flexibility of the cornea during the healing Table I lists the results of post-operative period and is therefore more marked in the unaided visual acuity and where there has older patient with slower healing, particularly been decay of effect up to 12 months the in the higher myopic group.