[Possibilities of prophylaxis of the induced "suture" astigmatism in cataract extraction]

Due to a number of reasons, the traditional methods of cataract extraction, i.e. through 8-12 mm limbic incisions, are still widely used in the clinical practice. A frequent occurrence of a high postoperative astigmatism, even if the operation is successful, is the main shortcoming of different variations of the traditional method of cataract extraction. Possibilities of how to neutralize the induced "suture-like" corneal astigmatism were investigated in this study by using two methods: A. a modified technique of applying a continuous corneal Pirs' suture with elements of an accentuated impact in the projection of the horizontal meridian. B. Meridian keratorraphia--application, in the cornea, of an additional compensatory suture in the projection of the horizontal meridian. Studies were made in two groups of patients after extracapsular cataract extraction (ECE) with intraocular lens (IOL) implantation--a total of 30 patients, 30 eyes. The main group was divided into two subgroups--A and B--(10 patients and 10 eye in each) in accordance with a used method of compensating the induced astigmatism. 10 patients were in the control group. A comparative evaluation of changes of a degree of the original astigmatism, which occurred under the influence of the sealing suture, showed that the parameters of induced astigmatism in the control group essentially and reliably (p < 0.001) exceeded the similar parameters registered in both subgroups of the main group; finally, the efficiency of method B in respect to neutralizing the "suture" astigmatism out did the possibilities of method A (p < 0.01).

A new lamellar wound configuration for penetrating keratoplasty surgery

A modified penetrating keratoplasty procedure with a new lamellar configuration of the surgical wound was performed on 8 eyes with endothelial decompensation. This technique allows complete suture removal by 3 months postoperatively, substantially shortening the time necessary for visual rehabilitation. Refractive astigmatism before and after suture removal was minimized to 4 diopters or less in all of the eyes in our preliminary series. Because the anterior surface of the donor button is smaller than the posterior one (diameter, 7.0 mm and 9.0 mm, respectively), more endothelial cells can be transplanted while maintaining the anterior graft surface at a safe distance from the corneoscleral limbus. Finally, no expensive instrumentation is required for this procedure except for an artificial anterior chamber if whole globes are not available. The surgical technique and clinical results are presented in this article.

Study of corneal topographic patterns with single continuous suturing techniques in penetrating keratoplasty

PURPOSE

To study the corneal topographic patterns following three different types of single continuous suturing techniques in penetrating keratoplasty.

METHODS

One hundred forty-eight maps obtained from 40 patients who underwent penetrating keratoplasty with single continuous suturing were retrospectively analyzed at a tertiary eye care center. The videokeratograph maps were obtained on the Eye Sys System 2000 at 1, 3, and 6 months after surgery. Suture adjustment was done for cases with astigmatism greater than 3 diopters, and maps were also obtained after suture adjustment. The maps were classified according to the corneal profile and the astigmatic pattern seen in the topographic maps.

RESULTS

Combined prolate patterns were seen most frequently, and their proportion was significantly higher at 1 month ( p= 0.009), 3 months ( p= 0.0004), and 6 months ( p= 0.0008). The simulated keratometric astigmatism was significantly higher in the prolate group compared with the other groups at 1 month ( p= 0.0021). However, all the topographic patterns showed comparable magnitude of astigmatism after suture adjustment and at 3 and 6 months. The antitorque suturing technique showed a higher proportion of prolate maps compared with the other suturing techniques.

CONCLUSIONS

Prolate patterns of the cornea are the most frequently seen patterns after single continuous suturing, which is the normal physiological pattern of the cornea. The initial astigmatism is higher in the prolate pattern, which can be successfully reduced with suture adjustment.

Prevalence rates and epidemiological risk factors for astigmatism in Singapore school children

PURPOSE

This study examined the prevalence rate of astigmatism and its epidemiological risk factors in Singapore school children.

METHODS

In a study of school children aged 7 to 9 years old in two schools in Singapore in 1999, a detailed questionnaire was administered to parents regarding reading or close-work habits, past history of close-work, family history, and socioeconomic factors. Cycloplegic refraction was performed five times in each eye. Defining astigmatism as worse than or equal to 0.5, 0.75, and 1 D cylinder in the right eye, the prevalence of astigmatism was calculated.

RESULTS

The study population consisted of 1028 children. The prevalence rate of astigmatism (worse than or equal to 1 D cylinder) was 19.2% (95% confidence interval, 16.8 to 21.6). This was not different between genders, ethnic groups, or age (p > 0.05). With-the-rule astigmatism was more common than against-the-rule astigmatism. The prevalence of astigmatism and myopia was 9.8% (95% confidence interval, 8.0 to 11.6). A high AC/A ratio was associated (p = 0.003) with astigmatism, even after exclusion of myopic children. On vectorial analysis, J0 and J45 were associated with the number of hours of playing video games, whereas J45 was also associated with computer use. Only J45 was associated to male gender, a high AC/A ratio, and a family history of myopia.

CONCLUSIONS

The prevalence rate of astigmatism (> or = 1 D) was 19%. Playing video games and computer use may be associated with astigmatism severity, although the presence of astigmatism (> or = 1 D) was not associated with any nearwork factors. A family history of myopia was associated with oblique astigmatism severity. A high AC/A ratio is associated with astigmatism, and this requires further investigation.

Long-term functional and topographic results seven years after epikeratophakia for keratoconus

PURPOSE

To analyze the long-term effect of epikeratophakia (EKP) on corneal topography and visual acuity of eyes with keratoconus.

METHODS

Retrospective study of 36 eyes 7.2 years after EKP. Four eyes underwent penetrating keratoplasty (PKP) and were excluded from further evaluation. Best-corrected visual acuity (BCVA) values were obtained from 32 eyes, corneal refraction and astigmatism from 23 eyes, surface asymmetry index (SAI) and surface regularity index (SRI) from 17 consecutive eyes that were operated upon after 1991, when the Tomey Topographic Modeling System became available.

RESULTS

Only four eyes needed PKP. In addition to EKP six eyes had compression sutures and/or relaxing incisions, and one eye underwent photorefractive keratectomy. Mean refractive power of the cornea decreased from 51.8 to 45.8 and astigmatism from 7.2 to 3.8. SAI improved from 3.2 to 0.9 and SRI from 3.7 to 0.9. Mean BCVA was 0.3 preoperatively and 0.6 upon last follow-up.

CONCLUSIONS

EKP was able to render PKP unnecessary in 32 of 36 eyes during the entire observation period. It was successful in permanently flattening the ectatic cornea and reducing astigmatism while restoring a symmetrical and smooth corneal surface. As a result, visual acuity improved considerably. In view of the young age of keratoconus patients needing surgery, and the fact that the lifetime of full-thickness corneal grafts is limited, EKP should be considered a valuable alternative to PKP in contact-lens-intolerant cases of keratoconus without central scarring.

Reduction of Spherical Aberration: Experimental Model of Photoablation

PURPOSE

Several authors have suggested that a compound ablation for myopia may reduce postoperative spherical aberration. This technique consists of treating myopic ablation by increasing the preoperative sphere 25% and applying a hyperopic ablation of 25% of preoperative sphere. Theoretically, this technique allows optical zone increase, and elimination of the peripheral red ring.

METHODS

Eight eyes of four patients with bilateral moderate myopia received laser epithelial keratomileusus (LASEK) with the Nidek EC-5000 excimer laser. In each patient, one eye was treated with the compound ablation (Group 1), and the fellow eye with the standard cross-cylinder technique (Group 2). Mean preoperative refraction and BSCVA were comparable within the two groups.

RESULTS

At 1 month postoperatively, UCVA was significantly better in Group 2 than in Group 1 eyes. In neither group was clinically important haze seen. Subjectively, all patients rated more satisfactorily the eye that received the standard ablation (Group 2) than the one treated with compound ablation (Group 1). Evaluation of keratorefractive indices derived from corneal topography revealed significantly better eccentricity in Group 2 eyes. Corneal topography showed the presence of a central island in all Group 1 eyes.

CONCLUSION

The compound ablation hypothesis was not confirmed. Presence of central island in compound-treated eyes induced significant optical aberrations.

Surgically Induced Astigmatism After Laser in situ Keratomileusis for Spherical Myopia

PURPOSE

To study risk factors for surgically induced astigmatism (SIA) after laser in situ keratomileusis (LASIK).

METHODS

In a retrospective case control study of 104 eyes (52 patients) that underwent LASIK for myopia (spherical ablation alone), two groups were studied: 42/104 eyes with SIA, and controls (62/104 eyes). The main variables studied were preoperative refraction, corneal thickness, preoperative keratometric power, amount of ablation, ablation zone diameter, flap thickness, flap size, and the presence of complications. The effect of SIA on visual performance was also evaluated.

RESULTS

The mean myopia for which LASIK was undertaken was -4.50 +/- 2.04 D. Mean scalar astigmatism induced was 0.35 +/- 0.50 D at 1 month, 0.33 +/- 0.40 D at 3 months, and 0.16 +/- 0.60 D at 6 months. SIA based on refractive cylinder was 0.66 +/- 0.29 D at 1 month, 0.54 +/- 0.32 D at 3 months, and 0.49 +/- 0.34 D at 6 months. Mean axis of vector induced astigmatism was 82.5 degrees +/- 57 degrees at 1 month, 98.86 degrees +/- 52.4 degrees at 3 months, and 113.9 degrees +/- 62.6 degrees at 6 months. Risk factors associated with the occurrence of SIA were preoperative keratometric power of >44 D [OR (95% CI); 1.97 (0.62 to 6.26)], ablation zone diameter of <6 mm [OR (95 % CI) 2.76; (0.6 to 12.6)], and suction ring diameter of 8.5 mm [OR (95% CI) 12.46; (2.0 to 77.38)]. The occurrence of SIA had no significant effect on uncorrected Snellen high contrast visual acuity, contrast sensitivity, and glare in comparison with controls.

CONCLUSION

Surgically induced astigmatism was more likely to occur with the use of smaller suction rings of 8.5 mm and in ablation zones less than 6 mm. Parameters for visual performance were not affected by the presence of surgically induced astigmatism.

A laboratory model for microkeratome-assisted posterior lamellar keratoplasty utilizing a running graft suture and a sutureless hinged flap

PURPOSE

To evaluate changes in anterior corneal curvature and graft stability with different sized donor buttons in a laboratory model of posterior lamellar keratoplasty.

METHODS

Thirty-six human eye bank corneas (18 donors and 18 recipients) were mounted on an artificial anterior chamber. A manual microkeratome was used to create a hinged anterior lamellar keratectomy. A 7.0-mm diameter posterior lamellar disk (posterior stroma, Descemet's membrane, and endothelium) was then trephinated from the recipient cornea. Three different sizes (7.0, 7.25, and 7.5 mm) of donor buttons were compared. They were sutured into the recipient bed with a running 10-0 nylon suture and covered by the host corneal flap. The flap was replaced without sutures. The resulting endokeratoplasty was analyzed by computerized videokeratography and tonometry.

RESULTS

Regular postoperative astigmatism was present in all cases. There was an average increase in astigmatism of 1.47 +/- 1.49 diopters (D) postoperatively. The mean change in the average keratometry readings was -5.12 +/- 6.12 D. The grafts and flaps maintained watertight seals with average leak pressures of 66.9 +/- 46.4 mm Hg. Although donor buttons oversized by 0.5 mm had the least change in average keratometry reading, those oversized by 0.25 mm had the best stability at high pressure. All groups had little change in astigmatism.

CONCLUSION

The optimal sized button of those tested would be either oversized by 0.25 or 0.5 mm. This new surgical technique may result in lower risk of high and irregular astigmatism in the management of corneal endothelial disorders.

[Causes, prognosis and prevention of cicatrical corneal astigmatism]

Penetrating wounds of the eyeball in 57-66% cases are associated with corneal involvement leading to the development of cicatricial astigmatism and decrease of the functional results. We investigated the causes of posttraumatic cicatricial corneal astigmatism, possibilities of its prediction, prevention, and correction. The results of treatment of 256 patients with corneal wounds and cicatrices are analyzed. Our analysis confirmed that the severity of astigmatism in corneal wounds directly depends on the wound size, edge status, direction, location, and structure of the forming cicatrix. Adequate and timely primary debridement of the corneal wound with intraoperative keratometric control plays the key role in minimization of cicatricial astigmatism. Early therapy with drugs stimulating the regeneration processes promotes more complete recovery of corneal tissue structure and decrease of astigmatism severity. Timely dosed slackening or removal of sutures makes possible modulation of astigmatism development. A formula is proposed, using which makes it possible, on the basis of initial data on the corneal wound, to estimate the possibility of corneal astigmatism, i.e. predict the outcome of the injury.

Referral rates for a functional vision screening among a large cosmopolitan sample of Australian children

The aim of this study was to investigate the incidence of functional vision problems in a large unselected cosmopolitan population of primary school-age children and to investigate whether constant clinical criteria for functional vision problems would be implemented by the practitioners involved in the screening. Refractive errors, near point of convergence, stereopsis, strabismus, heterophoria and accommodative facility were assessed for 2697 children (3-12 years) of varying racial backgrounds living in Australia. The spherical component of the refractive error ranged from -7.75 to +9.50 D (mean +0.54 D, +/-0.79) with a distribution skewed towards hypermetropia; astigmatism ranged from 0 to 4.25 D (mean -0.16 D, +/-0.35). There was a trend towards less hypermetropia and slightly more astigmatism with age. Mean near point of convergence was 5.4+/-2.9 cm, heterophoria at far and near was 0.12+/-1.58delta exophoria and 1.05+/-2.53delta exophoria, respectively, 0.55% of children exhibited vertical phoria at near >0.5delta, accommodative facility ranged from 0 to 24 cycles per minute (cpm) (mean 11.2 cpm, +/-3.7), stereopsis varied from 20 to 800 s (") of arc with 50% of children having 40" or better. The prevalence of strabismus was particularly low (0.3%). Twenty percent of the children were referred for further assessment based on criteria of one or more of: stereopsis >70", accommodative facility <8 cpm, near point of convergence (NPC) >9 cm, near exophoria >10delta or near esophoria >5delta, shift in eso or exophoria > or = 4delta between distance and near, astigmatism > or = 1 D, myopia more than -0.75 D, or hyperopia >+1.50 D. Post-hoc analysis of the record cards seeking the reason for further assessment indicates that referrals appear to have been based upon clinical intuition rather than on a set number of borderline or unsatisfactory results.

Technique to minimize asymmetric suture placement during penetrating keratoplasty

PURPOSE

Surgeons must mark the donor and recipient tissues precisely during penetrating keratoplasty, and verify the correct position of these marks in the actual donor button and trephine sites to minimize asymmetric placement of the graft within the host wound.

METHODS

A unique surgical reticule has been developed that simplifies proper marking of both the donor and recipient tissues with gentian violet. The reticule is placed within the oculars of the operating microscope. The circumference of the donor tissue and partial-thickness trephined host wound are aligned with a 5 mm inscribed circle. Eight equidistant lines, separated by 45 degrees around the circle, are used to place marks on the donor tissue and confirm the correct peripheral placement of limbal lines on the host tissue. The surgeon uses these landmarks for cardinal suture placement.

RESULTS

The reticule is easy to use with any size of trephine, and does not interfere with other surgical maneuvers during surgery.

CONCLUSIONS

Correct suturing of the first eight cardinal sutures can occur only if the donor button is marked after it has been prepared, and the location of the recipient marks are verified after the actual trephination impression has been made. This reticule should minimize the role of asymmetric suturing on final graft astigmatism.

Suturing technique for control of postkeratoplasty astigmatism and myopia

PURPOSE

We previously demonstrated that selective suture removal reduces keratoplasty astigmatism; however, a myopic shift was induced with increasing number of interrupted sutures removed. This study is an attempt to determine the effects of a modified surgical technique on postkeratoplasty myopia, astigmatism, and anisometropia.

METHODS

Optical penetrating keratoplasties were performed on 92 eyes of 84 patients. The study group consisted of 92 consecutive penetrating keratoplasties performed using 12 interrupted 10-0 nylon sutures and a tight 12-bite continuous suture, and use of an average keratometry (K) reading of 46.00 diopters for eyes undergoing combined and intraocular lens (IOL) exchange procedures. All patients had refraction, keratometry, and videokeratoscopy postoperatively, starting at 6 weeks and at the completion of selective suture removal.

RESULTS

Prior to suture removal, the average spherical equivalent was -0.160 +/- 3.59 diopters. It was -1.58 +/- 3.66 diopters at the completion of suture removal at 1 year and -1.44 +/- 3.72 at the last follow-up visit, averaging 20.7 months. Final residual refractive, keratometric, and videokeratoscopic astigmatism was 2.81 +/- 1.82, 4.19 +/- 2.94, and 3.58 +/- 2.03 diopters, respectively. Anisometropia, using the spherical equivalent of the operated and fellow eyes, was 2.49 +/- 2.25 diopters at completion of the study. A best corrected visual acuity of 20/50 or better was achieved in 50 patients (59%).

CONCLUSIONS

Low myopic spherical equivalent refraction and anisometropia with moderate residual astigmatism were achieved by using tighter continuous sutures, an average K reading of 46 diopters for calculation of IOL power, and selective removal of fewer sutures.

[Postmortem evaluation of corneal astigmatism after astigmatism oriented penetrating keratoplasty]

BACKGROUND

Reduction of astigmatism following penetrating keratoplasty can be achieved if the graft is oriented according to astigmatism parameters in donor and host (AOPKP). Postmortem evaluation of these parameters is therefore essential. The aim of our investigation was to compare postmortem measurements using a hand-held keratometer with those of the living donor's astigmatism.

METHOD

The 72-year-old female patient had undergone AOPKP on her right eye. After death the astigmatism in the right eye was evaluated 4.5 h postmortem using a hand-held keratometer. After explantation, the eyeball was examined by computer-assisted topography (TMS-1).

RESULTS/CONCLUSION

We could show that hand keratometry in situ is reliable for evaluating astigmatism in donor eyes after death. As far as our AOPKP study is concerned, these results are of great interest. Reduction of postoperative astigmatism following penetrating keratoplasty is only possible if data on astigmatism of the donor and host corneas are available.

Optimal incision sites to obtain an astigmatism-free cornea after cataract surgery with a 3.2 mm sutureless incision

PURPOSE

To determine the optimal incision to eliminate astigmatism after cataract extraction.

SETTING

Hara Eye Hospital, Utsunomiya, Japan.

METHODS

Patients having cataract extraction through a 3.2 mm corneal limbal incision without limbal sutures were divided into 2 groups. Group 1 comprised 98 eyes of 80 patients without preoperative astigmatism and Group 2, 72 eyes of 62 patients with no astigmatism postoperatively. In Group 1, the incisions that caused postoperative corneal changes were retrospectively evaluated. In Group 2, the types of incisions that induced an astigmatism-free cornea postoperatively were retrospectively studied. Patients were examined preoperatively and 6 months postoperatively.

RESULTS

In Group 1, 23 of 40 eyes (57.5%) with an incision between 9 and 12 o'clock (BENT incision) and 10 of 58 eyes (17.2%) with an incision at 12 o'clock remained astigmatism free postoperatively (P <.0001). One eye (2.5%) with a BENT incision and 17 (29.3%) with a 12 o'clock incision had astigmatism greater than 1.0 diopter (D) postoperatively (P <.001). In Group 2, 72 eyes had less than 1.2 D of preoperative astigmatism. No eye with more than 1.2 D of astigmatism was astigmatism free postoperatively, even when the incision was made at the steepest meridian.

CONCLUSIONS

The results indicate that to reduce astigmatism in eyes with preoperative astigmatism of 0.5 D or more, a limbal 3.2 mm BENT incision should be placed at 10:30 o'clock. To prevent astigmatism postoperatively, the incision should be placed at the steepest meridian in eyes with preoperative astigmatism greater than 0.5 D; for preoperative astigmatism greater than 1.2 D, a 3.2 mm incision at the corneal limbus is insufficient and a wider incision or an additional incision is required.

Keratometric results during the first year after keratoplasty: adjustable single running suture technique versus double running suture technique

BACKGROUND AND OBJECTIVE

To compare the 3-month and 1-year postoperative keratometric results in a retrospective sequential series of corneal grafts performed with either a double running suture technique or an adjustable single running suture technique.

MATERIALS AND METHODS

Keratometry values obtained 3 months and 1 year after penetrating keratoplasty, when sutures were still present, were compared between 31 grafts with double running sutures and 27 grafts with single running sutures, 15 of which had been adjusted postoperatively.

RESULTS

No significant difference in mean keratometry between the 2 groups was found either 3 months or 12 months after keratoplasty. Mean keratometric astigmatism was significantly less in the single running group at both 3 months (2.2 +/- 1.9 vs 4.5 +/- 2.8, mean +/- SD, P <0.001) and 12 months (3.0 +/- 2.2 vs 4.2 +/- 2.1, P = 0.03). Within groups, there was no significant change from 3 months to 12 months in either mean keratometry or keratometric astigmatism.

CONCLUSION

The single running suture technique, with postoperative adjustments, produced less keratometric astigmatism during the first postoperative year, when sutures were still in place.

[Postoperative induced astigmatism]

PURPOSE

Is to evaluate the astigmatism induced by cataract surgery, ethiological factors and ways of prophilaxies and treatment.

MATERIAL AND METHOD

We followed a number of 211 eyes operated for cataract by planned extracapsular extraction with intraocular lens implantation, in Ophthalmological Clinic from Cluj-Napoca. All the pacients had limbal incision and the suture was performed with 9.0 suture, after the operation the treatment consisted in local drops with steroids. REZULTS: The astigmatism induced by the surgery was direct in 53.08% of cases and indirect in 46.92%. The position of the axes was 0-900 in 72.51% and oblique in 27.48%. The optical correction of astigmatism was with combined spherocylinder glases in 57.34% and only with cilinder in 42.65% of cases.

CONCLUSIONS

1. The induced astigmatism by cataract surgery is in relation with the incision, suture and IOL. 2. Correction of astigmatism is possible with optical correction, repearing the suture or with refractive surgery. 3. The prevention of astigmatism over 1.5 D is by using Troutmann keratometer and to evidence the congenital astigmatism.

[Removal of congenital persistent pupilary membrane with sutureless clear corneal small incision]

PURPOSE

To investigate a new way in the treatment of serious congenital persistent pupilary membrane.

METHODS

In four cases of six eyes, after temporal clear corneal tunnel incision was made, viscoelastic material was injected into the anterior chamber, and the persistent pupilary membrane was cut down at the very point connected to the iris.

RESULTS

There is no ocular hypertention and hyphema after operation. After one year's follow-up, the lens remained transparent in 3 cases(4 eyes). There was corneal astigmatism of 0.12 to 0.25 D after operation. And only a few corneal endothelial cells were lost.

CONCLUSION

There are few postoperative complications and corneal astigmatism to incise congenital persistent pupilary membrane by temporal clear corneal tunnel incision. It is an ideal way to treat serious persistent pupilary membrane.

Microkeratome-induced reduction of astigmatism after penetrating keratoplasty

PURPOSE

To report the reduction in postpenetrating keratoplasty astigmatism with the use of the microkeratome to create a lamellar corneal flap as the first stage in a two-step laser in situ keratomileusis.

METHODS

The hansatome microkeratome was used to create a lamellar corneal flap in a 24-year-old man with a net corneal astigmatism of 7.3 diopters, 2 years after penetrating keratoplasty. No laser ablation was performed.

RESULTS

The net corneal astigmatism reduced to 3.9 diopters at 1 month and 2.3 diopters at 3 months of follow-up, without any laser ablation.

CONCLUSION

Laser in situ keratomileusis may be performed as a two-stage procedure, because the lamellar corneal flap alone may reduce postpenetrating keratoplasty astigmatism.

The preliminary clinical observation of array multifocal intraocular lens implantation

PURPOSE

To evaluate the clinical effects of implantation of Array multifocal intraocular lenses.

METHODS

Thirty-one cases (37 eyes) of cataract patients, including 15 males (19 eyes) and 16 females (18 eyes), were involved in this study. All patients underwent standard phacoemulsification with Array multifocal intraocular lens implantation. The complications during operation, postoperative distant visual acuity, near visual acuity, corneal curvature and visual symptoms were observed.

RESULTS

The mean value of best postoperative visual acuity was recorded as follows: uncorrected distant visual acuity was 0.8, the best-corrected distant visual acuity was 0.9, uncorrected near visual acuity was 0.5, near visual acuity with distant-corrected was 0.6, the best-corrected near visual acuity was 0.9. The astigmatism of cornea was less than 1.5 D pre-operatively and post-operatively. One patient complained of glare.

CONCLUSION

Array multifocal intraocular lens can provide good distant and near visual acuity. With observation of more cases and follow-up of longer time, we can draw a further conclusion.

[A research of infant refraction in Kunming Municipality]

OBJECTIVE

To study the infant refraction, detect ametropia in mass screening refraction and correct the ametropia properly for the treatment and prevention of amblyopia and strabismus as early as possible.

METHODS

The refraction status of 1 146 children (2 291 eyes, aged 1 month -3 years) were determined with retinoscopy after tropicamide cycloplegia.

RESULTS

The results of statistics showed that 89 eyes (3.88%) had emmetropia, 2 139 eyes (93.37%) hypermetropia, 38 eyes (1.66%) myopia, 560 eyes (24.44%) astigmatism and 25 eyes (1.09%) mixed astigmatism. In cases with ametropia, most of them were mild, and 97 eyes (4.23%) were moderate and severe. Anisometropia occurred in 34 infants (2.97%), and 7 infants (11 eyes, 0.48%) had strabismus. The degree of hypermetropia decreased with the increase of age. The percentage of astigmatism decreased with the age increase (chi(2) = 7.46, P<0.01), and the degree of astigmatism also decreased with the age increase (chi(2) = 26.1l, P < 0.01). Myopia increased with the age increase (chi(2) = 4.06, P < 0.05).

CONCLUSIONS

The prevention of amblyopia and strabismus in children should begin at the infant period, and the cases with moderate and severe ametropia should wear eye glasses as early as possible.

Step-along vergence procedures in stigmatic and astigmatic systems

The traditional step-along vergence procedure applies to stigmatic systems, that is, systems that are not astigmatic. Computation is disrupted when a focus coincides with a thin lens or refracting surface. A small change to the procedure results in a modified procedure which overcomes the computational problems. The modified procedure is easier to execute than the traditional procedure and allows one to write down useful equations directly. Among the formulae are those for back-vertex power. A step-along vergence procedure also exists for astigmatic systems. It makes use of the dioptric power matrix and the reduced vergence matrix. Computational problems arise when a point or line focus coincides with a thin lens or refracting surface; however they are not overcome by an analogous modification to the procedure. Nevertheless the modified procedure has some advantages including the fact that, as for stigmatic systems, it allows one to write down useful formulae directly. Stepwise calculations of vergence are sometimes performed backward through a system; the advantages and disadvantages described for step-along procedures holds for such step-back procedures as well.

Controlling astigmatism in cataract surgery requiring relatively large self-sealing incisions

PURPOSE

To evaluate the results of a modified self-sealing incision for achieving astigmatic neutrality in cataract surgery requiring a 6.0 to 7.0 mm incision as well as the methods of correcting preexisting astigmatism using these incisions.

SETTING

Department of Ophthalmology, Kushimoto Rehabilitation Center, Kushimoto, Japan.

METHODS

To achieve astigmatic neutrality, a frown-shaped, oblique incision-the BENT (between 9 and 12 o'clock) frown-was used. To reduce preexisting against-the-rule or with-the-rule astigmatism, the incisions were placed on the temporal or superior steep astigmatic axis, respectively. A frown incision was used when aiming for mild astigmatic reduction and an arcuate incision when aiming for relatively large astigmatic reduction.

RESULTS

In the 6.0 to 7.0 mm BENT frown incision group, mean flattening was minimal throughout 6 months of follow-up, with a maximum of 0.18 diopter (D) 1 week postoperatively. Surgically induced astigmatism was less than that with other incisions. Ninety-four percent of cases had a difference in absolute astigmatism of less than 0.50 D between preoperatively and 6 months postoperatively. Relatively large flattening was observed in eyes with 6.0 to 7.0 mm steep-axis incisions of superior arcuate, temporal arcuate, superior frown, and temporal frown, with means of 1.03, 0.79, 0.64, and 0.52 D, respectively, at 6 months. Ninety-eight percent of cases had a reduction in preexisting absolute astigmatism postoperatively.

CONCLUSIONS

In cataract surgery using relatively large scleral self-sealing incisions, the BENT frown incision effectively achieved astigmatic neutrality. The incisions on the temporal or superior steep astigmatic axis (with selective shape) reduced astigmatism in almost all cases.

Manual multi-phacofragmentation through a 3.2 mm clear corneal incision

PURPOSE

To evaluate the postoperative astigmatism and complications after manual multi-phacofragmentation (MPF) cataract surgery through a 3.2 mm clear corneal incision (CCI).

SETTING

Department of Ophthalmology, Hospital General de Segovia, Segovia, Spain.

METHODS

In a retrospective study, 50 eyes of 50 patients had cataract surgery by MPF. Patients were divided into 3 groups according to type of cataract. This technique uses a racquet-shaped nucleotome, a spatula, and 2 manipulators, right and left, for nuclear fragments. With these instruments, the nucleus is fragmented into multiple small pieces that are extracted from the anterior chamber. Astigmatism was evaluated before surgery and 7 days and 1 and 3 months after surgery by Gaussian distribution (P <.05). Intraoperative and postoperative complications were recorded.

RESULTS

Mean postoperative astigmatism was 0.77 diopters (D) +/- 0. 29 (SD) at 7 days, 0.47 +/- 0.22 D at 1 month, and 0.21 +/- 0.22 D at 3 months. During surgery, 2 cases (4%) of slight transient intracameral bleeding in the anterior chamber occurred. After surgery, 5 eyes (10%) had corneal edema, 2 (4%) had iritis, and 3 (6%) had ocular hypertension.

CONCLUSION

Using MPF, soft and hard nuclei can be removed through a 3.2 mm CCI. The astigmatic results were favorable and the complications few.