Repeated radial keratotomy

38 cases 59 eyes received repeated radial keratotomy in which the secondary incisions were performed along the scars of old incisions. The average follow-up after the reoperation was 13 months. Before reoperation, the mean spherical equivalent of the refraction was -3.78D and the mean keratometry was 40.15D. 13 months after the reoperation, the mean spherical equivalent of the refraction decreased by 2.30D, and the mean keratometry decreased by 2.04D. After the reoperation, the mean uncorrected visual acuity increased by 5 lines. There was no relationship between the therapeutic effect of the reoperation and the degree of initial myopia or pre-reoperative keratometry. The repeated radial keratotomy can decrease the degree of astigmatism and its complications are few.

Refractive aspects of cataract surgery

Cataract surgery has progressed to the point where it can now be performed so as to leave most patients emmetropic or with a predetermined amount of ametropia. The two major factors responsible for this prediction accuracy are intraocular lens power calculation and the control of surgically induced astigmatism. Recent theoretical intraocular lens power formulas are more accurate owing to their improved methods for predicting the postoperative anterior chamber depth. Additionally, there are more reliable methods for determining surgically induced astigmatism as well as methods for its control. Various combinations of wound architecture, wound closure, and astigmatic keratotomy and their effect on surgically induced astigmatism are reviewed.

Astigmatism after cataract surgery: nylon versus Mersilene. Five-year data

This is a follow-up of a previous study that evaluated astigmatism after cataract surgery. In that study with a six-month follow-up, there was no statistically significant difference in astigmatism between eyes with nylon sutures and those with polyester fiber (Mersilene) sutures. This article reports the five-year data on this series of eyes.

A new cornea-marking device for penetrating keratoplasty and refractive corneal procedures

In penetrating keratoplasty, postoperative astigmatism is determined by a number of factors, including adaptation of wound edges, mode of trephination of both donor and patient cornea and, last but not least, suture techniques. We would like to introduce a new cornea-marking device for use in keratoplasty and epikeratophakia. This device helps the surgeon to center the trephine and to perform a perfect double running torque-antitorque suture. Additional single sutures are not necessary. A study of postoperative astigmatism following operations in which this device was used is under way.

Long-term natural and modified course of surgically induced astigmatism after extracapsular cataract extraction

A prospective study was carried out to investigate the long-term course of surgically induced astigmatism after extracapsular cataract extraction. Sixty-one eyes were followed for 36 months. In 27 eyes with post-operative astigmatism > 4D with-the-rule, one or two sutures were cut in the steeper meridian after 3 months. In another group of 34 eyes with only minor or no postoperative astigmatism with-the-rule, no suture was cut. We found that 1) postoperative astigmatism was significantly increased in all eyes after 1 week and 3 months, but decreased in time approaching preoperative values after 3 years, 2) surgically induced astigmatism was with-the-rule at 1 week and 3 months but turned against-the-rule in time in both groups. Astigmatism decay rate was significantly steeper in eyes with suture cutting, 3) the keratometric axis was exclusively with-the-rule after 1 week, but turned against-the-rule in both groups, approaching the preoperative distribution of axis after 3 years. We concluded that surgically induced astigmatism is a dynamic feature showing changes in size and axis even in the period 1-3 years postoperatively. Suture cutting seems to intensify the decrease in the induced astigmatism and accelerate the shift in astigmatic axis, turning astigmatism against-the-rule compared to eyes with intact sutures.

Relaxing incisions with compression sutures for control of astigmatism after penetrating keratoplasty

BACKGROUND

Ten per cent of patients with persisting postoperative astigmatism following penetrating keratoplasty (PK) require surgical re-intervention, despite an otherwise "successful" transplant. Relaxing incisions (RIs) in combination with compression sutures seem to be the preferable procedure. However, poor predictability and lack of long-term experience complicate the issue. Here we report the 2-year follow-up results of 25 patients with high PK astigmatism treated by means of RIs and compression sutures.

METHODS

Commonly, free-handed RIs were placed at the graft-host interface and 10-0 nylon compression sutures were placed perpendicular to the incisions. PK sutures had been removed no less than 4 months prior to refractive surgery.

RESULTS

Nineteen eyes regained a functional vision of > or = 0.4. The net decrease in astigmatism was 6.1 +/- 4.3 D (47 +/- 21%). The mean vector-corrected change in astigmatism was 13.1 +/- 5.7 D. Cylinder axis variation was reasonably low, with a correlation of attempted versus achieved axis of r = 0.85. Within the first 3 months after operation the induced astigmatism regressed by, on average, 5.5 +/- 4.3 D, making intraoperative overcorrection necessary. As an inevitable side effect, refractive procedures resulted in a myopic shift (4.7 +/- 6.9 D) in spherical equivalence.

CONCLUSION

RIs and compression sutures are very useful in reducing postkeratoplasty astigmatism if correction of extremely high cylinder (> 10 D) is not intended. However, predictability still remains unsatisfactory and more than one operation may be required.

Corneal topographic analysis of superolateral incision cataract surgery

Using corneal topography, we compared the corneal shape changes following superolateral incision cataract surgery with those following conventional superior incision surgery. In our superolateral incision procedure, a 6.5 mm limbal incision was made from the 9 o'clock to 11 o'clock meridians to avoid incising the superior limbus. One hundred four patients were divided into two groups; Group 1 comprised 66 patients who had surgery using the superolateral approach; Group 2 comprised 38 patients who had surgery using the superior approach. The corneas were examined by keratometer and topographic modeling system preoperatively, and at one week and one, three, and six months postoperatively. Keratometric measurements showed that surgically induced astigmatism (SIA) in Group 1 was significantly less than that in Group 2 throughout the six-month observation. The standard SIA deviation in Group 1 was also smaller than that in Group 2, indicating a smaller degree of variability in the superolateral incision surgery. In the corneal topographic analysis, a color-coded map averaging all the Group 1 corneas at each interval showed a slight steepening in the central cornea in the 10 o'clock meridian one week after surgery. This surgically induced steepening disappeared by one month, and the corneal shape recovered its preoperative shape. In contrast, the Group 2 averaged map showed a marked steepening of the upper and lower corneas. The steepening gradually decreased but remained until three months after surgery. Superolateral incision surgery induced a smaller degree of change in the corneal shape, as well as in SIA, than superior incision surgery. The postoperative corneal shape changes disappeared rapidly after the superolateral incision, and the corneal shape soon stabilized and recovered its preoperative shape.

Randomized clinical trial comparing astigmatism and visual rehabilitation after penetrating keratoplasty with and without intraoperative suture adjustment

PURPOSE

The authors performed a prospective, randomized clinical trial to compare postoperative astigmatism and visual rehabilitation after penetrating keratoplasty with and without intraoperative suture adjustment.

METHODS

Twenty-five patients undergoing penetrating keratoplasty for avascular corneal pathology randomly were assigned to two groups. All surgery was performed by one surgeon (ONS) using the same technique (except for intraoperative suture adjustment) with Hanna trephination (8 mm) and a running 10-0 nylon suture. Postoperative suture adjustment was done during the first postoperative month in all patients who had more than 3.5 diopters of astigmatism. Refraction and computerized topographic analysis were performed at 1 and 6 months postoperatively.

RESULTS

Intraoperative suture adjustment significantly decreased postkeratoplasty topographic (P = 0.0001) and refractive (P = 0.0001) astigmatism and improved best spectacle-corrected visual acuity (P = 0.0019) during the first postoperative month. Seventy-seven percent of control patients (mean topographic astigmatism, 4.89 +/- 1.99 D at 1 month), but no patients who underwent intraoperative suture adjustment (mean topographic astigmatism, 1.50 +/- 0.74 D at 1 month), required at least one postoperative suture adjustment that delayed optical stability and increased postoperative complications. At 6 months postoperatively, mean topographic (P = 0.06) and refractive (P = 0.0001) astigmatism were smaller in the intraoperatively adjusted group than in the control group with postoperative suture adjustments. After intraoperative adjustment, best spectacle-corrected visual acuity was better (P = 0.0168, P = 0.0434) and corneal topography was more regular (P = 0.02, P = 0.07, NS) at 1 and 6 months, respectively, than after postoperative adjustment.

CONCLUSION

Visual rehabilitation with decreased postkeratoplasty astigmatism and more regular corneal topography was attained more rapidly and safely with intraoperative suture adjustment.

The use of the same size host and donor trephine in penetrating keratoplasty for keratoconus

The results of a retrospective analysis of 49 eyes (40 patients) that underwent penetrating keratoplasty for keratoconus are presented. All grafts had the same size trephine for both host and donor corneas. Ninety-eight per cent of eyes achieved a post-operative visual acuity of 6/12 or better; 43% of eyes attained this level of acuity unaided, although more than half of these required spectacles or contact lenses to reach their best corrected acuity. The average post-operative spherical ametropia was -0.5 dioptre (SD 2.97 dioptres) and the average post-operative cylinder was -3.8 dioptres (SD 2.63 dioptres). Three eyes (6%) required keratorefractive surgery to reduce astigmatism. Wound integrity was satisfactory using the same (size) trephine for both host and donor, with no patient suffering a post-operative wound leak or iris prolapse. The reduction of post-operative myopia and astigmatism is discussed.

Some mechanical properties of 10/0 monofilament nylon sutures

A short pilot study is described which investigates some of the mechanical properties of ophthalmic sutures. The Alcon 10/0 monofilament nylon suture was found to behave in a mechanically consistent manner. Like all nylon it possesses the property of 'creep', which helps to compensate for overtightening of the section during surgery.

Refractive stability after cataract extraction using a 6.5-millimeter scleral pocket incision with horizontal or radial sutures

BACKGROUND

Radial suturing of 6.5-millimeter scleral tunnel incisions following cataract surgery can create significant with-the-rule astigmatism in the immediate postoperative period. Because of the significant visual distortion and slow visual recovery seen with radial suturing, this study was undertaken to compare two other suturing techniques which induce lesser amounts of with-the-rule astigmatism in the immediate postoperative period.

METHODS

The refractive behavior of eyes closed with loose radial sutures and with horizontal sutures was compared to the behavior of eyes closed with the more traditional "tight" radial sutures following phacoemulsification surgery.

RESULTS

Eyes sutured with loosely tied radial sutures demonstrated minimal with-the-rule cylinder immediately following surgery (1.25 D) and showed a more rapid stabilization of astigmatism than did the eyes tied with tight radial sutures, 2 months versus up to 6 months. However, the eyes tied with horizontal sutures, which showed no induced with-the-rule astigmatism at the time of surgery, showed even more rapid stabilization between 5 days and 1 month from the time of surgery.

CONCLUSION

To get the most rapid visual rehabilitation following cataract surgery, a wound closure which generates no induced with-the-rule cylinder such as horizontal sutures would be required.

Corneal sutures: is routine removal really necessary?

Three groups of patients were reviewed 1, 2 and 3 years after extracapsular cataract extraction to assess the incidence of problems related to nylon corneal sutures and the need for suture removal. A large percentage of patients were found to have suture-related problems and required or had previously undergone suture removal. These findings are analysed. The potential risk of sight-threatening pathology associated with corneal sutures that are left in situ suggests that routine suture removal about 3 months after surgery is to be recommended.

Refractive error and ocular motility in plagiocephaly

Plagiocephaly, which is caused by premature closure of one of the coronal sutures, leads to fronto-orbital asymmetry. The aim of this work was to study the repercussions of orbital deformation on the visual system. Twenty-one patients presenting with plagiocephaly at birth and operated on by the same craniofacial technique (bilateral approach with translation and advancement of the entire involved orbits) were included in the study. All of the patients were examined by clinical anthropometry with three-dimensional reconstruction and underwent complete eye examination by the same observer. Follow-up after craniofacial surgery ranged from 15 months to 4 years. In the last few years, three-dimensional reconstruction has shown that the anatomic region affected by the deformation is the frontozygomatic region and has thus made it possible to advance to another theory on the origins of ocular problems. The severe effect of orbital anomalies on the development of the visual system (binocular vision, strabismus with amblyopia, refractive errors) has been emphasized in the literature. The present study shows that the scheduling of reconstructive surgery is fundamental and must not exceed 6 months, given the immaturity of the visual system up until this time. This means that the ophthalmologist must be able to recognize the various craniostenoses in order to schedule reconstructive surgery as soon as possible. Cooperation between the neurosurgeon and the ophthalmologist is of paramount importance if the pathogenic effects of this bone deformation are to be stopped and proper visual development preserved.

Suture adjustment in penetrating keratoplasty

Postoperative adjustment of a single running penetrating corneal graft suture was done in 19 patients (22 adjustments). The short-term effect of this procedure was a mean reduction of corneal astigmatism of 4.39D (p < 0.0001). Thereafter, the corneal contour was fairly stable, provided that the running suture remained intact and tight. Localized loosening of the graft suture significantly increased the corneal astigmatism. Following removal of the graft suture no statistically significant mean change of corneal astigmatism was found. However, patients with a previously intact running suture tended to show increased astigmatism, while those with a previous localized suture loosening usually showed a decreased astigmatism after suture removal. The main benefit of suture adjustment is apparently the rapid and fairly stable reduction of postkeratoplasty astigmatism usually obtained, but unfortunately this effect seems chiefly to exist only as long as the graft suture remains intact and tight.

A comparison of two semi-quantitative surgical keratometers: the modified Hyde ruler and the Barrett keratoscope with "astigmatic dial"

The Hyde astigmatic ruler is an inexpensive, semiquantitative, hand-held, surgical keratometer that we modified by geometrically calculating the correct shape of its ellipses. The Barrett keratoscope is a cheap, disposable, qualitative keratometer that, unlike the Hyde ruler, produces a bright corneal image. We designed a transparent overlay, or "astigmatic dial," to use with the keratoscope. This overlay determines the magnitude of astigmatism and sets the distance the keratoscope is held from the cornea by direct comparison with the corneal image. Using a model cornea, we compared our modified Hyde ruler with the Barrett keratoscope and astigmatic dial to determine the accuracy of measurement provided by each. Both instruments had good predictive values for the true astigmatism; however, the Barrett keratoscope/astigmatic dial provided more consistent measurements of the astigmatism. We believe the keratoscope and dial provide a cheap, convenient, and accurate alternative to the more expensive microscope-mounted keratometers.

[A report of 412 consecutive posterior chamber intraocular lens implantations]

The series of 412 consecutive PC IOL implantations comprised 337 eyes of senile cataract, 16 eyes of membranous cataract, 25 eyes of traumatic cataract, 13 eyes of congenital cataract, 10 eyes of complicated cataract and 11 eyes of aphakia. 362 eyes were postoperatively followed up from 4 weeks to 1 1/2 years with the results that 251 (69.3%) eyes obtained visual acuities of 0.8 or over, and 328 (90.6%) eyes 0.5 or over. The authors discussed the technical improvement in anterior capsulotomy and the implantation procedures in cases of posterior capsule rupture. The importance of postoperative control and management of astigmatism, in the recovery of visual acuity was pointed out.

Normalisation of asymmetric astigmatism after intralesional steroid injection for upper eye lid hemangioma in childhood

Infantile hemangiomas affect about 5% (3%-8%) of the population, showing a predilection for the face. After a phase of rapid enlargement between the 3rd and the 9th month of life, 70% regress by the age of six after a period of stability. 43%-60% of the children with eye lid hemangiomas develop strabismic, anisometropic, or deprivation amblyopia. Previous studies found the majority of cases resulting from anisometropia (especially asymmetric astigmatism) rather than strabism or occlusion of the visual axis. Several methods of treatment--surgical excision, irradiation, sclerosing agents, systemic steroids, ligation, cryotherapy--have been used but all with a risk of local or systemic complications. Local injections of steroids are a simple method of therapy with a high rate of resolution of hemangiomas, but still with a high degree of bad visual output because of persistent astigmatism. In four children with asymmetric astigmatism (axis of astigmatism towards the hemangioma) in which the injection was given at the beginning of the phase of enlargement, amblyopia could be avoided by preventing corneal steepening from becoming permanent.

Factors influencing the accuracy of the SRK formula in the intraocular less power calculation

Several intraocular lens (IOL) power calculation formulas (either theoretical or empirical) are used to determine the emmetropic IOL power) The Sanders-Retzlaff-Kraff (SRK) linear regression formula is among the most widely recognized empirical ones. In the present study intraocular lens power calculation aiming at emmetropia was performed, using SRK formula, in 145 cataractous eyes undergoing lens implantation. The final refraction was evaluated at 8 to 12 months after surgery. The purpose of this study was the identification and quantitative evaluation of the factors which influence significantly the accuracy of SRK in the intraocular lens power calculation. The following factors were studied: (1) the error in preoperative biometry with regard to the difference between post and preoperative axial length measurements, (2) the position of the implantation of the intraocular lens (anterior versus posterior chamber), (3) the intraocular lens style, (4) the intraocular lens power level, (5) the preoperative corneal astigmatism, (6) the surgically induced corneal astigmatism, and (7) the postoperative astigmatism. Multiple regression and stepwise regression analysis showed a strong correlation (R2 = 0.65; p < 0.001) between postoperative refractive error (Rf) and error in preoperative biometry (delta AL), surgically induced corneal astigmatism (SIA) and postoperative astigmatism (Ap) only. This correlation is expressed by the following equation: Rf = 0.07 -2.55 delta AL -0.42 SIA + 0.34 Ap. This equation indicates the quantitative effect of each factor on the accuracy of the SRK formula, by defining the pattern of the fluctuations of the amount or state (myopic or hyperopic) of refractive error induced by changes of variables delta AL, SIA and Ap.

The comprehensive control of astigmatism during and following intraocular lens implantation

The operating corneoloscope and Terry operative keratometer were used respectively in 29 and 34 eyes during the intraocular lens implantation to measure the corneal astigmatism qualitatively or quantitatively, so that the tension of incision closure could be adjusted. The surgically induced astigmatism in qualitative group two weeks after the operation was 3.5 +/- 1.70 D and that in quantitative group was 2.56 +/- 1.60 D. There were 55.17% and 38.24% of the eyes with over 2.00 D corneal astigmatism in qualitative and quantitative group two months after the surgery. The astigmatism of both groups at the early stage after the operation was significantly lower than that of the control group (p < 0.05). Argon laser, Nd:YAG laser or razor-blade were used to cut 1 to 3 limbal sutures in 64 eyes with over with-the-rule astigmatism 2.25 D at the early stage (2 months) after the operation. One hour after suture cutting, the with-the-rule corneal astigmatism reduced significantly with an average of 2.61 D. The astigmatism continued to reduce and stabilized one month after the suture cutting. The arcuate keratotomy was performed in 21 eyes, of which the postoperative astigmatism was over 2.25 D (with the average of 3.34 D) more than 6 months after IOL implantation. The mean astigmatism was 0.82 and 1.18 D one day and 6 months after the keratotomy respectively. The uncorrected visual acuity improved significantly after the keratotomy. These results indicate that applying corneoloscope or Terry keratometer to adjust the tension of incision closure during operations, selected suture cutting at the early postoperative stage, and performing arcuate keratotomy at the late postoperative stage be the effective methods to reduce surgically induced corneal astigmatism.

Astigmatic decay following small incision, self-sealing cataract surgery

A series of 22 consecutive patients had phacoemulsification using a small (3.5 to 4.0 mm), self-sealing incision. Preoperative keratometric analysis was performed using the EyeSys photokeratoscope. Results of this analysis were compared with keratometric data obtained at one week and at one month postoperatively. These comparisons were evaluated for surgery-induced cylinder and astigmatic decay at the 3, 5, and 7 mm corneal zones. At one week postoperatively, there was only mild against-the-rule change in cylinder at each corneal zone, and these changes showed minimal decay at the one month follow-up visit.