Early post-LASIK macular and peri-optic disc
Observation of epithelial changes of optic nerve
Wang Hongge Dong Xiaoguang Zhang Tao Wang Jinliang Tian Jingyi Fu Lijing* Studio Ophthalmology Wang Hongge
【Abstract】Objective To compare the changes in retinal volume in specific areas of the macula and the thickness of the macula and peripapillary optic nerve fiber layer in the early postoperative period before and after LASIK using OCT. Methods OCT was performed in 59 eyes of 31 myopic patients before and on the first day after surgery to measure the thickness of the central macular recess, the thickness of the optic nerve fiber layer above, below, nasal, and temporal in four directions around the macula and optic disc, and the volume of the retina in the 6-mm diameter area of the macula. The results showed that the thickness of the optic nerve fiber layer in the center of the macula and above the optic disc became thinner after LASIK compared with that before surgery, and the P values were 0.003 and 0.016, respectively, which were statistically significant. Conclusion: There was a statistically significant thinning of the thickness of the optic nerve fiber layer in the center of the macula and above the optic disc in the early postoperative period after LASIK, while there was no statistically significant effect on the retinal volume in specific areas of the macula and the thickness of the optic nerve fiber layer in other areas around the macula and optic disc.
Keywords】Laser in situ keratomileusis, optical coherence tomography, retinal nerve fiber layer thickness
Evaluating the change of peripapillary and perimacular retinal nerve fiber layer (RNFL) in the very early stage after LASIK
WANG Hongge DONG Xiaoguang ZHANG Tao WANG Jinliang FU Lijing*
Shandong Eye Hospital, Jinan,Shandong Province PRC 250021
FU Lijing: Qingdao Municipal Hospital , Shandong Province PRC 266071
ABSTRACTS
Objective: To evaluate the influence of laser in situ keratomileusis (LASIK) on the macular retinal volume , peripapillary and perimacular retinal nerve fiber layer (RNFL) thickness assessed by optical coherence tomography (OCT) preoperatively and 1 day postoperatively.
Methods: 31 myopia patients with 59 eyes were included. The RNFL thickness and macular retinal volume measurements were performed using optical The RNFL thickness and macular retinal volume parameters were compared using The RNFL thickness and macular retinal volume parameters were compared using paired-sample T test.
Results: the RNFL thickness of macular fovea and superior area around optic disc significantly decreased postoperatively, P value is 0.003 and 0.016 respectively; inferior average, nasal average around the disc and temporal average around macular 6mm circle increased postoperatively, but the change is not significant. Other area decreased postoperatively , No significant change was observed .
Conclusions: Laser in situ keratomileusis (LASIK) significantly decrease the RNFL thickness of central macular fovea and superior area around the But it did not significantly affect macular retinal volume and the peripapillary & perimacular retinal nerve fiber layer (RNFL) thickness. The LASIK Ophthalmologic Layer (RNFL) thickness postoperatively except the area mentioned above.
【key words】 LASIK OCT RNFLT
Laser in situ keratomileusis (LASIK) has been widely used in the treatment of myopia, but during the process of corneal flap fabrication, the intraocular pressure changes dramatically. The effect of LASIk on the thickness of the retinal nerve fiber layer has been observed using OCT, but no clear conclusion has been made so far. In the present study, we performed preoperative and postoperative retinal optic nerve layer thickness and macular area retinal volume measurements using OCT on a more comprehensive area of the retina to observe the effect of LASIK surgery on the optic disc and macular area nerve fiber thickness.
Materials and Methods
I. Data
There were 31 patients who underwent LASIK surgery in our hospital, 17 males and 14 females; age ranged from 18 to 36 years old, mean age 21.16 years old; 3 were monocular, 28 were binocular, total 59 eyes; spherical lens prescription ranged from -0.75 to -8.25 D, mean -3.96 D, of which All patients were operated by the same surgeon with LASIK using excimer laser TECHNOL S217 from Bausch & Lomb, with an attraction time of 20-50 seconds and an average of 32 seconds.
II. Methods
In addition to the routine LASIK examination, the OCT Stratus Model 3000 from Zeiss and its accompanying Version 4.0.4 (0073) software were used to measure the thickness of the retinal optic nerve layer and the volume of the retina in the macular region at specific ranges, including the central macular recess, 3 mm and 6 mm diameters centered on the macula and 4 mm diameters centered on the optic disc. The thickness of the nerve fiber layer was measured at 13 sites in four directions: above, below, temporal, and nasal, and the volume of the retina in the macula was measured at 6 mm diameter. The OCT was performed by the same experienced examiner, and the measurements were taken on the first postoperative day in addition to the usual examinations.
III. Statistical treatment
The data obtained preoperatively and postoperatively were analyzed using paired t-test. Statistical calculations were done by SPSS 11.5 software. differences were significant at P < 0.05.
Results
The data measured using OCT, including the central macular recess, the thickness of the nerve fiber layer at a total of 13 loci in four directions: above, below, temporal, and nasal in the macula centered at 3 mm and 6 mm diameters and in the optic disc centered at 4 mm diameters, and the retinal volume in the macular area at 6 mm diameters, were analyzed by paired t tests. The preoperative and postoperative changes in the thickness of the nerve fiber layer in the central macular recess (MF) were statistically significant (t=3.144, P=0.003<0.05); the preoperative and postoperative changes in the thickness of the nerve fiber layer in the 4-mm-diameter circle above the optic disc (OD-S) were statistically significant (t=2.488, P=0.016<0.05); the remaining points The preoperative and postoperative changes in nerve fiber layer thickness and retinal volume in the 6-mm diameter area of the macula were not statistically significant (see Table 1).
Discussion
Laser in situ keratomileusis (LASIK) has been widely used in the treatment of myopia, and although its safety has been recognized by ophthalmologists and myopic patients, some minor and major complications can still occur. Among them, ocular complications have been widely studied and recognized, while less research has been done about the effects on the vitreous and retina. There are reports of postoperative placoid macular detachment [1], temporary macular edema [2] and visual field damage [3], thus the effects of LASIK surgery on the vitreous and retina remain to be further investigated.
During the LASIK procedure, the IOP during the flap creation is over 60 mmHg, which is higher than the normal IOP of about 40 mmHg or more for about 20-50 seconds, with an average of 30 seconds, what is the effect of this rapid change in IOP on the vitreous retina? Previously, OCT has been used to observe the effect of LASIk on retinal nerve fiber thickness, and the postoperative observation time was generally chosen to be 1 week, 2 weeks or even 1 month after surgery [2] and 3 months [4], and the results were mostly an increase in retinal nerve fiber layer thickness after surgery than before surgery, but not statistically significant [5,7]; the observation site was mostly chosen to be in one part of the macula. What about the changes in retinal nerve fiber layer thickness in the early postoperative period? Is there any effect on the thickness of the retinal nerve fiber layer at sites other than the macula? What is the change in retinal volume within a specific area of the macula? Therefore, we measured retinal nerve fiber thickness and retinal volume at several sites, including the macula and optic disc, on the first postoperative day. The results showed that retinal optic nerve fiber thickness was generally thinner on the first postoperative day than before surgery, and the degree of thinning at two sites, the center of the macula and above the optic disc, was statistically significant, consistent with the reports of Tsai YY and Lin JM [6]. Due to the effect of transient ultrahigh intraocular pressure, which causes volume and shape changes in intraocular tissues to adapt to the high IOP environment, the retina adapts to the elevated IOP by thinning, but the degree of change is not consistent at each site. An increase in optic nerve fiber thickness compared to preoperative at one week, two weeks, or even one month after surgery has been reported abroad [7] and in China [5], but it was not statistically significant. Combining the results of the present study and the previous ones, it seems to be speculated that different parts of the optic nerve fiber layer showed different degrees of thinning in the early postoperative period compared with the preoperative period, and after a certain period of time, the optic nerve fiber layer gradually showed different degrees of thickening in response to short-term high IOP, and then returned to the preoperative thickness by a sufficient time after surgery. This change, although present, did not have a significant impact on ocular anatomy or function. Thus, the results of this study have important implications for our overall understanding of the effects of transient high intraocular pressure on the retina during LASIK surgery.
References
1. Singhvi A, Dutta M, Sharma N, Bilateral serous macular detachment following laser in situ keratomileusis. Am J Ophthalmol. 2004 Dec;138(6):1069-71.
2. Yang B, Wang Z, Huang G, Transient macular edema after laser in-situ keratomileusis. Yan Ke Xue Bao. 2003 Mar;19(1):20-4.
3. Bushley DM, Parmley VC, Paglen P. Visual field defect associated with laser in situ keratomileusis[J].Am J .ophthalmol,2000,129;668-671
4.Dementyev DD, Kourenkov VV, Rodin AS, Retinal nerve fiber layer changes after LASIK evaluated with optical coherence tomography. J Refract Surg. 2005 Sep-Oct;21(5 Suppl):S623-7.
5. Chen XG, Zhao J, He Shouzhi et al. OCT measurement of retinal nerve fiber layer thickness before and after LASIK. Chinese Journal of Laser Medicine. 2004-11;13(4): 205-207.
6. Tsai YY, Lin JM. Effect of laser-assisted in situ keratomileusis on the retinal nerve fiber layer. Retina. 2000; 20(4):342-5.
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Table 1 Comparison of OCT measurement parameters before and after LASIK surgery in 59 eyes
Department Preoperative mean (um) Postoperative mean (um) T-value P-value
MF 193.0847 189.1186 t=3.144 P=0.003
MRV 6.7620 6.7510 t=0.602 P=0.549
M3-S 273.9661 273.7457 t=0.309 P=0.759
M3-N 270.7797 269.6271 t=0.792 P=0.432
M3-I 257.5932 266.5423 t=0.092 P=0.927
M3-T 257.5932 256.3728 t=1.007 P=0.318
M6-S 253.6780 235.8475 t=1.824 P=0.073
M6-N 253.6780 253.4237 t=0.221 P=0.826
m6-i 222.8644 221.8305 t=0.524 p=0.602
M6-T 214.5593 215.2203 t=-0.617 P=0.540
OD-S 139.25 135.229 t=2.488 P=0.016
OD-N 69.42 70.65 t=-0.677 P=0.502
OD-I 135.17 136.92 t=-1.143 P=0.259
OD-T 93.5 93.35 t=-1.384 P=0.173
Note: MF: macular center MRV: macula 6 mm diameter retinal volume M3-S: macula 3 mm circle above M3-N: macula 3 mm circle nasal M3-I: macula 3 mm circle below M3-T: macula 3 mm circle temporal M6-S: macula 6 mm circle above M6-N: macula 6 mm circle nasal M6-I: macula 6 mm circle below M6-T: macula 6 mm circle temporal OD-S : Optic disc 4mm circle above OD-N : Optic disc 4mm circle nasal side OD-I : Optic disc 4mm circle below OD-T : Optic disc 4mm circle temporal side. mvr unit is um3.