Comparison Of The Visual Outcome: 1.8 Mm Vs 3.0 Mm Incision Coaxial Phacoemulsification

PART I Assessment of predictive refractive error between target and actual refraction[Purpose] To determine the clinical factors affecting postoperative visual acuity; To evaluate the predictive refraction error and its influent factors.[Methods] This cohort study prospectively enrolled 60 patients (60eyes) who received cataract surgery and IOL implantion in Zhongshan Hospital between September 2013 and January 2014.The main outcomes were visual acuity(LogMAR), refraction and corneal curvature at pre-operative, 1d, 1w, 1m respectively. All statistical analyses were performed using Independent-sample T test, ANOVA analysis and linear-regression analysis with SPSS 17.0. P value less than 0.05 was considered statistically significant.[Results] 13.3% out of 60 patients gained BCDVA LogMAR>0.52 and 56.7% LogMAR<0.09 at 1d,80% LogMAR<0.09,1.7%(an AMD patient) LogMAR>0.52 at 1m. The postoperative Spherical equivalent (MRSE) were -0.78±0.08D、-0.89±0.05D、-0.82±0.05D at 1d, 1w and 1m. No statistical difference was found in MRSE after surgery (P>0.05), but it was better than preoperative (P<0.05). The mean absolute error(AE) was 0.64±0.04D D.18% of patients were within 0.25D,45% within 0.5D, and 80% within 1.0D. The mean predictive error (PE) calculated by SRK/T、Holladay-1、Haigis、Hoffer-Q formula were 0.26±0.07 D、0.49±0.08D、0.56±0.07D、0.59±0.09D, with significant difference between SRK/T and the other three formulas (P,=0.004, P2=0.021, P3=0.005) at 1m. PE calculated by SRK/T formula had no correlation with surgically induced astigmatism(SIA), age, LOCS grade and IOL type (P>0.05).while was associated with axial length (AL), the regression equation was y=-3.993+0.176×x(r=0.284, P=0.000). PE of different AL groups(22-24mm、24-26mm、26-28mm、 28-30mm、>30mm) were 0.14 ±0.06D、0.08±0.06D、0.92±0.06D、1.18±0.06D、1.78±0.10D, with statistical difference between groups (F=4.170, P=0.007). Anterior chamber depth (ACD) was found significantly correlated to PE. The regression equation was y=-1.788+0.670×(r=0.163, P=0.007). Corneal curvature was also associated with PE. The regression equation was y=7.752-0.168Xx(r=0.098, P=0.038). In addition, preoperative refraction was correlated to PE. The regression equation was y=0.163-0.038× x(r=0.098, P=0.039).[Conclusions] PE calculated by SRK/T is minimum compared with Holladay-1、 Haigis、Hoffer-Q formula. PE has no correlation with surgically induced astigmatism(SIA), age, LOCS grade and IOL type, while is associated with preoperative AL、ACD、corneal curvature and refraction.PART II Comparison of the Visual Outcome: 1.8 mm vs 3.0 mm incision coaxial phacoemulsification[Purposes] To compare the visual outcome of patients after coaxial phacoemulsification with 1.8 mm and 3.0 mm incision.[Methods] This cohort study prospectively enrolled 30 patients (30 eyes) in two groups, who received coaxial phacoemulsification with either 1.8 mm or 3.0 mm incision. Patients were recruited from cataract surgery patiens in Zhongshan Hospital from September 2012 to June 2013 and paired according to age and gender (1:1). The main outcomes were visual acuity, contrast sensitivity, endothelial cell count(ECC), refraction, astigmatism, aberrations, complications and mean average phaco power(AVG), average phaco time (APT), at pre-operative,1 day,1 week,1 month,3 months and 6 months. All statistical analyses were performed using Independent-Samples T Test and ANOVA analysis with SPSS 17.0. P value less than 0.05 was considered statistically significant.[Results] BCDVA was significantly better in 1.8mm group than in 3.0mm group at Id, lw. No statistical difference was observed after 1m(P>0.05). There was no differences in photopic and mesopic contrast sensitivity (1.0、1.7、2.6、4.2、6.6、10.4cpd)at Id, lm,3m(p>0.05). AVG and APT were smaller in 1.8mm group than in 3.0mm group. No statistical difference was detected with ECC loss at Id, 1w, lm,3m,6m (p>0.05). Spherical equivalent was significantly different between the two groups at 3m (p<0.05), while no difference was found with absolute error (AE), presbyopia, surgically induced astigmatism (SI A) (p>0.05).1.8mm incision lead to earlier Astigmatism recovery.which typically occurred within 1m. However, no statistical difference was observed between two groups after 3m(P>0.05). No statistical difference was found in RMS, HOA, Coma, Trefoil, astigmatism at pre, 1w, 1m,3m, while Spherical showed statistical differences at 1m,3m(P<0.05).[Conclusions] 1.8mm C-MICS shows smaller AVG, longer APT, less ECC loss, less surgery-induced astigmatism, and earlier improvement in visual acuity. Implanted with aSpher ical intraocular lens, C-MICS can reduce the Spherical like aberrations and total aberrations, gains better visual outcome than C-SICS.