|Year : 2022 | Volume
| Issue : 2 | Page : 147-151
Optimal Time for Spectacle Prescription after Uneventful Clear Corneal Phacoemulsification
Allapitchai Fathima1, Sadasivan K Samyukta2, Shivkumar Chandrasekaran3, Meenakshi Ravindran1, Ramakrishnan Rengappa4
1 Department of Paediatric Ophthalmology, Aravind Eye Hospital and PG Institute of Ophthalmology, Tirunelveli, Tamil Nadu, India
2 Government Medical College, Thrissur, Kerala, India
3 Cataract IOL Services, Aravind Eye Hospital and PG Institute of Ophthalmology, Tirunelveli, Tamil Nadu, India
4 Glaucoma Services, Aravind Eye Hospital and PG Institute of Ophthalmology, Tirunelveli, Tamil Nadu, India
|Date of Submission||29-Sep-2021|
|Date of Decision||10-Jan-2022|
|Date of Acceptance||18-Jan-2022|
|Date of Web Publication||30-Jun-2022|
Department of Pediatric Ophthalmology, Aravind Eye Hospital and PG Institute of Ophthalmology, Tirunelveli - 627 004, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Purpose: In this advanced era, patients prefer to have reliable spectacle prescription after phacoemulsification at the earliest possible time. The purpose of this study is to find out the period of refraction stabilization after uneventful phacoemulsification in a tertiary eye care hospital in south India. Methodology: A prospective nonrandomized observational study at a tertiary surgical eye care centre in South India was conducted from January to June 2018, on 210 eyes of 210 consecutive patients with senile cataracts, who underwent uneventful phacoemulsification through 2.8 mm clear corneal incision. The refraction status of the subjects was evaluated at 1st week, 3rd week, and 3rd month postoperatively. One hundred seven patients were followed up till 3rd month. The remaining patients were followed up to 1 month. Patients were grouped into 1, 2, and 3 based on power variations in the range of 0–0.25 D, 0.5–0.75 D, 1 D, and more difference between visits, respectively. The changes were analyzed for spherical and cylindrical powers separately. Results: Almost 98.1% and 96.2% of patients were in Group 1 among spherical and cylindrical powers, respectively, when compared between second and third visits. About 84.3% and 67.1% were in Group 1 among spherical and cylindrical powers, respectively, when compared between first and second visits, but the difference was not statistically significant. The mean spherical equivalent showed no difference between all the three visits. Conclusion: Since there is no statistically significant difference of spherical and cylindrical values between visits, our prospective study concludes that reliable final refraction both by autorefraction and subjective refraction for spectacle prescription is possible as early as 1 week, in cases of clear cornea and quiet eye at 1 week postoperatively.
Keywords: Glass prescription, phacoemulsification, refraction stabilization, spectacle prescription
|How to cite this article:|
Fathima A, Samyukta SK, Chandrasekaran S, Ravindran M, Rengappa R. Optimal Time for Spectacle Prescription after Uneventful Clear Corneal Phacoemulsification. TNOA J Ophthalmic Sci Res 2022;60:147-51
|How to cite this URL:|
Fathima A, Samyukta SK, Chandrasekaran S, Ravindran M, Rengappa R. Optimal Time for Spectacle Prescription after Uneventful Clear Corneal Phacoemulsification. TNOA J Ophthalmic Sci Res [serial online] 2022 [cited 2022 Aug 10];60:147-51. Available from: https://www.tnoajosr.com/text.asp?2022/60/2/147/349507
| Introduction|| |
Modern small incision cataract surgery with foldable intraocular lenses (IOL) is essentially a refractive surgery with the patients expecting the sharpest vision, at the earliest, in the postoperative period. Rapid stabilization of refractive errors if any translates to patient satisfaction with improved quality of life. For the best quality of vision after surgery, it is desirable that the patients use refraction correction for both distance and near. Hence, the prediction of time of stabilization of refraction designs the postsurgical refraction protocols.
In this study, we sought to determine the rate at which postoperative refractive errors stabilize after phacoemulsification through an unsutured temporal clear corneal incision with implantation of a three-piece, 5.5 mm optic, acrylic foldable IOL (AcrySof, Alcon).
| Methodology|| |
This was a prospective nonrandomized observational study at a tertiary surgical eye care center in South India. Two hundred and ten eyes of 210 consecutive patients with senile cataracts, attending the cataract and services IOL, who underwent uneventful cataract surgery by clear corneal temporal 2.8 mm incision phacoemulsification and foldable acrylic intraocular lens implantation, and who fitted into our inclusion criteria were recruited for the study at 1 week postoperatively. This study was conducted over 6 months between January and June 2018. All the surgeries were performed by the same method by five different surgeons using the Alcon Infiniti phacoemulsification device (Alcon Laboratories, Fort Worth, TX, USA) with Ozil torsional handpiece. All the surgeons were well experienced with phacoemulsification, as they have done more than 1000 phacoemulsification procedures. The IOL power calculation was done using SRK/T formula with the IOL master-500 (Carl Zeiss). All the recruits received the same postoperative treatment in the form of tapering dose of topical steroids – prednisolone acetate 1% over 6 weeks and topical antibiotics – ofloxacin 0.3% four times daily over a period of 2 weeks. Informed consent was obtained from all the recruits. The study adhered to the recommendations of the Declaration of Helsinki and obtained approval from the Institutional research board. Inclusion criteria were clear cornea at 1 week post surgery, quiet anterior chamber (mild iritis – Grade1), posterior chamber intraocular lens in the bag, normal intraocular pressure (IOP), and best-corrected visual acuity (BCVA) in the range (20/20.20/40). Exclusion criteria were prior ocular trauma, suture placement in the section or paracentesis, postoperative severe corneal edema, elevated IOP or severe iritis persisting for more than a week, capsular bag distension, IOL tilt or decentration, co-existing retinal or corneal pathology, preexisting amblyopia, or any other intraoperative complications. Those fulfilling the inclusion criteria were subjected to a complete ophthalmic evaluation including estimation of BCVA, autorefractometry, slit-lamp examination, and fundus examination at baseline and at all follow-up visits. The refraction status of the subjects was evaluated at 1st week, 3rd week, and 3rd month postoperatively. Initially, 107 patients were followed up at 1st week, 3rd week, and 3rd month. Since the results showed very less difference between 3rd week and 3rd month and moreover, the glass prescription cannot be postponed to 3rd month in this advanced era, the remaining 103 patients who were recruited later on were followed up to 3 weeks postoperatively.
The changes in the status of refraction were detected using an automated refractometer (KR 800-Topcon) and confirmed by subjective refraction. The values of subjective refraction were taken as a single refraction by autorefractometer before surgery to establish the baseline refraction. At subsequent visits, the mean of three consecutive autoshot measurements by the autorefractometer was taken as the final reading. The changes in refractive error were analyzed as changes in cylinder power, axis, and spherical power separately. To oversee the changes in spherocylindrical form, the changes in the mean spherical equivalent were compared using paired t-test. Accordingly, the variations in refraction in the cylindrical power, changes in axis, and changes in spherical power were classified into three categories with groups.
Variations in cylindrical power or spherical power
Group 1: No change to a difference of 0.25 D between baseline status and follow-up visits
Group 2: 0.5–0.75 D difference between baseline status and follow-up visits
Group 3: ≥1 D difference between the baseline status and follow-up visits (considered to be a significant difference as 1D change in refraction can reduce the unaided Snellen acuity by three lines).
Since a change in spherical or cylindrical power by 0.25 D will cause only negligible effect on vision, those in Group 1 were considered as having “no change” in this study.
Variations in cylinder axis
Group 1 – No change or change of axis < 10°
Group 2 – Change of axis by more than 10°.
Mean (Standard deviation) and frequency (%) were used to describe the summary data. Wilcoxon signed-rank test was used to access the mean difference of sphere, cylinder, and axis between 1st week, 3rd week, and 3rd month. P <0.05 was considered statistically significant. All the statistical analysis was performed by STATA 11.1 (Texas).
| Results|| |
Two hundred and ten patients including (102 male patients and 108 female patients) were analyzed in the study in the first two visits. Out of them, 107 patients were followed up to 3rd month.
It was observed that 98.1% [Table 1] and 96.2% [Table 2]of the patients fell in Group 1 category of change in spherical and cylindrical refractive errors, respectively when compared between 3rd week and 3rd month. Only 1.9% [Table 1] and 3.73% [Table 2] of patients fell in Group 2 category of spherical and cylindrical refractive error changes, respectively. There was none in Group 3. Since the difference in refractive error was meagre in the 3rd-week and 3rd-month postoperative visits, the remaining 103 patients were followed only up to 1 month.
When comparing between the visits one and two, 84.3%, 14.3%, and 1.4% of the recruits showed changes in spherical power falling in Groups 1, 2, and 3, respectively [Table 1]. About 67.1%, 22.9%, and 10% of the recruits showed changes in cylindrical power falling in Groups 1, 2, and 3, respectively [Table 2].
When the cylindrical axis difference was analyzed, 77.1% of the recruits were in Group 1 on comparison between visits one and two. Almost 97.1% of the recruits were in Group 1 on comparison between visits two and three [Table 3].
The analysis of mean spherical equivalent between each visit reveals no change in mean spherical equivalent between 1st week and 3rd week and only 0.04 difference between 3rd week and 3rd month, which was statistically not significant [Figure 1]. There is no change in the mean spherical equivalent in first and second visits. There is a slight change in the third visit, which may be due to a change in the number of patients during the third visit.
|Figure 1: The mean equivalent of spherical equivalents in each visit is marked as line diagram. There was no change in mean spherical equivalent while comparing between first and second visits, but there is a change in mean spherical equivalent while comparing between second and third visits|
Click here to view
The difference in values of sphere and cylinder was compared between 1st week and 3rd week, with 1st week and 3rd month. The P value using Wilcoxon signed-rank test (>0.05) shows that there is no statistically significant difference [Table 4].
| Discussion|| |
Modern cataract surgery aims at restoring vision with negligible postoperative refractive errors., Rapid stabilization of refractive errors improves the quality of life and enhances the level of satisfaction of the patients.,, The early prescription of glasses is essential for the patients to return to their workplaces earlier.
The changes in refraction associated with cataract surgery and IOL implantation can be attributed to multiple factors. The eyes with longer prescribing times have wounds which take a longer time to reach sufficient strength to stabilize refraction. Changes in anterior chamber depth and IOL position and IOL optic configuration also attribute to the refractive error changes post phacoemulsification. Deepening of anterior chamber is probably related to capsulorrhexis shrinkage and is associated with hyperopic shift. Adhesions between the anterior and posterior capsules cause forward movement of the IOL and myopic shift follows. These IOL position-related factors due to capsular fibrosis cause changes in refractive errors only after few months. Moreover, the phacoemulsifications done by experienced surgeons with an optimum overlap of rhexis over IOL will prevent these changes in long term. Hence, we have not taken these factors to account as these will not influence the spectacle prescribing time in early postoperative period.
Capsular bag distension alters the anterior chamber dimensions. Furthermore, lens decentration and tilt induce changes in spherical as well as cylindrical refraction.
Hence, these cases were not included in our study.
In our study, the spherical and cylindrical refraction changed to within 0.25 D in the majority of the recruits when refraction was assessed by autorefractometer and confirmed by subjective refraction, and compared between follow-up visits at 1 week and 3 weeks following uneventful phacoemulsification with IOL implantation surgery for senile cataract. The change in cylindrical axis noted over the first and second postoperative visits was negligible, within 10°, thus suggesting stabilization of refraction as early as 1 week. Our study did not aim at evaluating the surgically induced astigmatism and was specifically directed to evaluating the stabilization of refractive error for prescribing spectacle correction.
In a prospective study by Fukuda S et al., it is said that using 3D corneal OCT, the architecture of clear corneal wound stabilizes by 1 week post surgery. We feel that the wound stabilization by 1 week is the reason for refraction stabilization by 1 week in our study.
A few retrospective studies have studied refraction stabilization after phacoemulsification,,, but not many have studied spherical and cylindrical refraction changes separately.
Sugar et al. conducted a retrospective analysis of 100 consecutive patients post uncomplicated phacoemulsification with foldable IOL insertion. They studied the change in spherical equivalent refractive error, which at 1st-week follow-up was within +/-0.50 D of the 4th-month refraction in 66.1% of eyes and the cylinder was within +/-0.50 D in 72.9%. At 1 month, the corresponding values were 87.1% and 85.7%.
In the study by Lake et al., refraction stabilization was noted as early as 1 week, similar to the findings of our study. They demonstrated that the subjective refraction outcome changed minimally between 8 days and 15 days of cataract surgery and that it may be possible to prescribe spectacles after 1 week to most patients who had uneventful phacoemulsification. However, this was a retrospective study conducted on a relatively small sample of 30 consecutive patients.
Ionides and Claoue found that 70% of eyes had a change of 0.50 D or less from 2 to 6 weeks after surgery and a mean refractive change of 0.34D between these two visits with a modal change of 0. They suggested the prescription of corrective spectacles as early as 2 weeks, thus reducing the number of postoperative visits by the patient thereby reducing their financial burden.
Caglar et al. reported stabilization of spherical and cylindrical refraction at 1 week post phacoemulsification on 62 consecutive patients with senile cataracts. It was a prospective study that also depended on autorefractometer values for assessing refraction status and suggested spectacle prescription after 2 weeks of cataract surgery.
De Juan et al. studied that automated refraction outcome, spherical and cylindrical refraction separately (using ARK-30 Nidek Co. LTD, Aichi, Japan) changed minimally from the 1st week when compared with values taken at 1st month postoperatively. They concluded that automated refraction alone was highly repeatable and could be used to monitor postsurgical refractive changes. The same study also suggested that spectacle correction can be given as early as 1 week after surgery. They suggested that different refractions can have the same spherical equivalent; hence, evaluation of spherical equivalent as reported in other studies, reduces the accuracy in assessing the refractive outcome of the cataract surgery. Similarly, the mean spherical equivalent compared between 1st week and 1st month in our study showed no difference. Hence, we also felt that separate evaluation of spherical and cylindrical errors will allow better accuracy as compared to evaluation of spherical equivalent alone; thereby, our study employed both autorefractometry and subjective refraction methods and analyzed spherical and cylindrical refractive errors separately. The separate analysis of sphere and cylinder also does not show a statistically significant difference between 1st week and latter visits at 3rd week and 3rd month. Moreover, when the difference of spherical and cylindrical power between 1stweek and 3rd week was compared with the values between 1stweek and 3rdmonth, there was no statistically significant difference stating that 1st-week refraction is equivalent to 3rd-month refraction.
The cases in our study were operated by five different experienced surgeons (who have done more than 1000 phacoemulsifications), unlike in other studies. Thus, the results can be generalized to cases of experienced surgeons. The earlier prescription benefits the patient by reducing the number of postoperative visits and enabling a faster return to routine work and recreational activities with lesser anisometropia and clearer vision.
The current study has its limitations in that it included only uncomplicated surgeries on senile cataracts in otherwise normal eyes. Further larger prospective trials are required for optimized refraction protocols post phacoemulsification and IOL implantation surgery in senile cataracts.
| Conclusion|| |
There were some changes present while evaluating spherical and cylindrical power separately, but statistically not significant, whereas the analysis of mean spherical equivalent revealed no change. Hence, reliable glass prescription can be given at 1 week postoperatively in cases of clear cornea. However, a word of caution has to be given regarding possible changes in spherocylindrical form if the patient prefers buying expensive glasses.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]