This study was a retrospective interventional comparative study that included 60 eyes of 30 patients. The included patients had bilateral microphthalmos with high axial hyperopia and had undergone a lens based surgical procedure for hyperopia correction. The included patients were equally divided into two groups. The first group (30 eyes of 15 patients) had undergone refractive lens exchange (RLE) with primary piggyback IOL implantation. The second group (30 eyes of 15 patients) had undergone RLE with maximum available IOL power implanted followed by a secondary implantation of Artisan iris-fixated IOL (Ophtec B.V., Groningen, The Netherlands). The inclusion criteria were having posterior microphthalmos defined as short axial length two standard deviations below the normal for the patient's age with normal corneal size and anterior chamber depth (ACD) and having complete records for 3 years follow up postoperative. For secondary Artisan iris-fixated IOL, ACD should be > 2.8 mm. Patients were excluded if they had intraoperative complications e.g. primary aphakia, incomplete data records, nanophthalmic eyes, microphthalmos with a corneal diameter less than 9 mm, microphthalmos with anterior segment dysgenesis syndrome, and posterior or combined types of persistent hyperplastic primary vitreous. Cases of macular scars and glaucoma were also excluded. Presence of papillomacular folds was not considered an exclusion criterion as it is commonly encountered in cases of posterior microphthalmos.
The current study was approved by the local ethics committee of the faculty medicine, Alexandria University, Egypt. Tenets of the Declaration of Helsinki were followed. All patients signed an informed consent explaining the procedure and possible complications.
Preoperative complete ophthalmic examinations were conducted including measuring corneal diameter, axial length, fundus examination for posterior segment abnormalities, and measuring intraocular pressure. Also, screening for systemic disorders was conducted. IOL power calculation was performed in all cases using optical biometry (IOL-master 500, Carl Zeiss, Germany) with Haigis formula. Records of the patients were revised, and all preoperative, operative and postoperative data was recorded. All patients were operated upon by the same surgeon (A.H.) with a reproducible technique.
Surgical technique:
All included cases had undergone a refractive lens exchange with corneal incisions created using a 2.4 mm keratome for main incision placed in all cases on the steep topographic axis as determined using corneal topography and 1.2 mm blade for the side ports. The anterior chamber was filled with viscoelastic. the continuous curvilinear capsulorhexis (CCC) was created with a capsulorhexis forceps. Lens aspiration was performed using minimum or no phaco power according to the nuclear density. Infinity® Phacoemulsification System (Alcon, USA) was used in all cases. Procedure was followed by IOL implantation of the maximum power available in the capsular bag after removal of the lens cortex: Tecnis -1 aspheric IOL (Advanced Medical Optics AMO) using its injector provided by the company. Careful removal of viscoelastic material from the anterior chamber was carried out in all cases followed by careful stromal hydration of all corneal wound.
The first group had primary implantation of piggyback silicon 3-piece IOL in the sulcus (Tecnis 3-piece, Advanced Medical Optics, AMO). The power of the piggyback IOL was calculated by subtracting the power of the already implanted IOL from the calculated IOL power and subtracting 0.5 D due to the change in the effective lens position because of sulcus placement. The second group had undergone another procedure after approximately 2 months in the form of a secondary implantation of Artisan iris-fixated IOL. The Artisan lens aphakia model 205 is a monofocal one-piece convex-concave PMMA IOL with an 8.5 mm length, a 1.04 mm maximum height, and a 5.0 mm optical zone. The haptics have grooves in which the iris can be enclavated. The available IOL powers available ranged from +2.0 to +30.0 D. The calculation of the IOL power was done based on the actual residual refractive error of the eye after RLE. The power calculations were based on the “Van der Heijde” formula. The 2ry Artisan implantation was done using the same standardized technique of phakic model. Two small corneal paracenteses at 3 and 9 o’clock were performed. Followed by a 5.5 mm corneo-scleral tunnel at 12 o’clock site. Insertion of the Artisan lens under the protection of a cohesive viscoelastic material in the anterior chamber was done followed by rotating the lens such that the haptics were opposing 3 and 9 o’clock positions. The lens was then held by the fixation forceps through the corneo-scleral tunnel and the midperipheral iris was enclavated into the haptics using an enclavation needle. The wound was closed with 10-0 nylon suture and the cohesive viscoelastic was washed. Suture removal was done 2 months postoperative.
Postoperative antibiotic and steroid eye drops were prescribed for one month. Patients were followed up at day 1, week 1, and months 1, 3, 6, 12, 18, 24 and 36. The main outcome parameters were manifest refraction, mean absolute error of prediction (MAE), uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), Snellen lines loss of CDV and predictability with percentage of eyes within 0.50 D and 1.0 D of intended correction. The MAE is calculated by the mean absolute value of the difference between intended and actual postoperative refraction.
Data analysis was performed using the software SPSS for Windows version 20.0 (SPSS Inc., Chicago, USA). Quantitative data were described using range, mean and standard deviation. Kolmogorov-Smirnov test was used for checking the normality of distribution. The independent sample t test was used to compare means of different samples. Paired t test was used for comparisons between means of the preoperative and postoperative data of the same eyes. Chi square test was used to compare between different percentages. Pearson correlation was used to correlate between different variables. Differences were considered statistically significant when the associated p-value was less than 0.05. Standard Figures for reporting the outcomes in refractive surgery, according to the Waring Protocol and its modification were used for displaying and summarizing the refractive outcomes of this study for each group postoperatively.