This study included 60 eyes of 32 myopic patients. Bilateral surgery was performed in 28 patients (87.5%) and unilateral surgery in 4 patients (12.5%). Eight patients were males (25%) and 24 were females (75%). The mean age of patients was 28.1±4.3 years (range: 21 - 32 years).
Anterior segment parameters by Pentacam: (table 1)
ACD and ACA was significantly reduced at all postoperative follow-up visits in comparison with preoperative value (P<0.001) with no significant difference between the different follow-up time points.
Mean preoperative ACV was 194.7±23.7mm3 and was significantly decreased to 127.2±20.7 mm3, 126.9±21.9mm3, and 127.9±21.3 mm3 in the postoperative 1st, 3rd and 12th months, respectively (P<0.001).
By the end of the follow up, the lens vault ranged from 240 to 540 µm with no statistically significant change throughout the different follow-up visits (Figure 1).
In comparison with preoperative values, postoperative mean CCT was significantly increased in the 1st and 3rd months (P<0.001) and (P= 0.013) respectively but it was significantly reduced in the 12th month (P=0.001).
Table 1: Anterior segment parameters by Pentacam:
|
Preoperative
|
1st month
|
3rd month
|
12th month
|
N=60
|
N=60
|
N=60
|
N=60
|
Angle
Range Mean ± SD
|
(34.9-50.7) °
(42.2±4.2) °
|
(18-33.9) °
(25.8±4.2) ° (A)
|
(17-33.9) °
(25.1±3.9) ° (A)
|
(16.8-33.6) °
(25.8±4.5) ° (A)
|
AC depth
Range
Mean ± SD
|
(3000-3450) µm
3205.3±133.5 µm
|
(2055-2600) µm
2364.7±162.9 µm (A)
|
(2030-2700) µm
2374.7±194.3 µm (A)
|
(2080-2700) µm
2371.3±187 µm (A)
|
AC volume
Range
Mean ± SD
|
139-216 mm3
194.7±23.7 mm3
|
94-176 mm3
127.2±20.7 mm3 (A)
|
96-176 mm3
126.9±21.9 mm3 (A)
|
93-173 mm3
127.9±21.3 mm3 (A)
|
Central corneal thickness
Range
Mean ± SD
|
(478-590) µm
523.7±35.3 µm
|
(473-599) µm
533.6±36.8 µm (A)
|
(476-592) µm
531.3±39.5 µm (A)
|
(476-585) µm
518.9±34.4 µm (A)
|
Vault
Median
IQR
|
|
420 µm
(330-520) µm
|
410 µm
(270-525) µm
|
420 µm
(240-540) µm
|
- Paired samples T test for parametric quantitative data between each 2 times.
- (A): significant difference in comparison with preoperative value (P value < 0.05).
- IQR: interquartile range.
Mean preoperative IOP was 13.7±1.8 mmHg which was increased to 17.2±2.3 mmHg in the 1st month and to 15.9±4.5 mmHg in the 3rd month. This was a statistically significant difference (P<0.001 and P=0.025, respectively). There was no significant difference between preoperative and postoperative mean IOP by the 12th month (P=0.163). Four eyes (6.66 %) had an elevated IOP (26-30 mmHg) that were treated with topical IOP-lowering medications (a combination of timolol and brimonidine) until the 2nd month, then IOP was controlled without medication. There was insignificant correlation between postoperative elevation of IOP and the reduction of ACD and ACA at different follow-up visits (Table 2).
Table 2: Correlation between IOP change and changes of ACA and ACD at postoperative follow-up.
|
|
IOP increase
|
r
|
P value
|
1st follow-up
|
ACA decrease
|
0.347
|
0.061
|
ACD decrease
|
-0.284
|
0.128
|
2nd follow-up
|
ACA decrease
|
0.181
|
0.337
|
ACD decrease
|
0.033
|
0.864
|
3rd follow-up
|
ACA decrease
|
0.261
|
0.163
|
ACD decrease
|
-0.253
|
0.178
|
- Pearson’s correlation
- *: Significant level at P value < 0.05
- IOP = intraocular pressure
- ACA= anterior chamber angle
- ACD = anterior chamber depth
Specular microscopy: (table 3)
Mean preoperative ECD was significantly decreased by the end of follow up (P < 0.001) with a percentage of decrease of 6.52±6.71%. There was also a statistically significant decrease in hexagonal cells (P = 0.033) and increase in CV (P = 0.040). A statistically insignificant negative correlation (r = -0.285) was found between the decrease in endothelial cell density and the decrease in ACD (P=0.126).
Table 3: Comparison between preoperative and postoperative endothelial cell density, hexagonal cells and CV.
|
|
Preoperative
|
12th month
|
P value
|
|
N=60
|
N=60
|
Endothelial cell density (cell/mm2)
|
Range
Mean ± SD
|
(2503-3377)
2929.3±248.1
|
(2193-3268)
2737.9±303.1
|
<0.001*
|
Hexagonal cells
|
Range
Mean ± SD
|
(57-73)
66.9±2.8
|
(61-72)
65.5±4.8
|
0.033*
|
CV
|
Range
Mean ± SD
|
(24-37)
28.4±2.6
|
(24-35)
29.8±3.9
|
0.040*
|
- Paired samples T test for parametric quantitative data between each 2 times.
- *: Significant level at P value < 0.05.
- CV= coefficient of variance.
IPCL was implanted upside down in 2 eyes (3.33%) and were managed by removal of IPCL, reloading, and reinjection in the proper orientation.
Throughout the study, no sight threatening complications occurred such as cataract, permanent glaucoma, endophthalmitis, or retinal detachment.
Visual acuity and refraction:
The mean Log-Mar UCVA significantly improved from 1.48±0.19 preoperatively to 0.46±0.11 postoperatively by the end of follow up (P<0.001) (Figure 2).
There was a statistically insignificant difference between the mean preoperative BCVA and postoperative UCVA (P=0.209) by the end of the 12th month. There was no statistically significant difference between mean postoperative UCVA and postoperative BCVA by the 12th month.
Cumulative Snellen postoperative UCDA shows that 7% had UCVA 6/18, 47% had UCVA 6/12, 40% had UCVA 6/9, and 6% had UCVA 6/6. Figure (3 A)
As regard changes in Snellen lines of CDVA, 66.7% showed no changes, whereas 26.7% gained one or more lines, and 6.7% lost one or more lines (Figure 3 C).
As regard refraction, spherical equivalent decreased from (-11: -16D) preoperatively to (-0.5: +1D) postoperatively with a statistically highly significant difference (P<0.001). There was no significant change in postoperative refraction throughout the follow up visits.
Post-operative spherical equivalent refraction at last follow up showed that 27% of patients became emmetrope, 7% became -0.25 D, 27% became -0.5D, 13% became +0.25 D, 20% became +0.5 D and 7% became +1D postoperative (Figure 3 B).