The Research Of Astigmatism In The Patients With Cataract

Part one The distribution of corneal astigmatism in the patients with cataractObjects To study the distribution of corneal astigmatism and the distribution of corneal Q value in the patients with cataract.Methods A retrospective analysis was performed of432cataract patients (663eyes) without having been suffered injury or performed operation.The degree and the axis of astigmatism were analyzed using the corneal topography.Results Significant correlations were found between the age(r=0.092,p=0.003<0.01),the older they are,the higher the degree of astigmatism is.But no significant correlations were found between the ECC and the CCT (p=0.781、0.223).There was no significant correlation between the gender and the degree of astigmatism(p>0.05),and there was no difference between the right eye and the left eye.54.6%eyes of these patients have less than1.0D of astigmatism,and26.2%are more than1.5D.And the percentage of astigmatism with the rule decreased with the age(from the group of<40years old with96.3%to the older than90with9.5%),but increased for astigmatism against the rule(from2.8%to85.7%).And there was no trend for oblique astigmatism. The mean corneal Q value was-0.26±0.40, Significant correlations were found between the curvature and CCT (r=-0.151,P=0.001),(r=-0.189,P=0.000),but no correlations were found between the age (r=0.014,P=0.768) and astigmatism (r=0.008,P=0.056).Conclusion In cataract patients, the degree of astigmatism increased with the age.And the pattern of corneal astigmatism shifts from with-the-rule to against-the-rule astigmatism. The corneal Q value of aged patients is in normal distribution, and showed a negative relationship with corneal curvature and CCT.Part two Clinical observation of astigmatism induced by2.2mm clear corneal incisional phacoemulsification with foldable IOL implantation and6.0mm small incision cataract surgery with intra-ocular lens implantationObjects To evaluate the changes of astigmatism induced by3.2mmsuperior corneal incisional phacoemulsification with foldable IOLimplantation.Methods Surgery was performed on94cases (94eyes)with2.2mm clear corneal incision and6.0mm small incision.The changes of corneal astigmatism before and3months after surgery were compared and we also calculated the surgically induced astigmatism3months after surgery.Results The average of corneal astigmatism was (0.96±0.80) D and (0.96±0.83) D before and three months after the operation respectively with2.2mm clear corneal incision.There was no significant difference, statistically (p>0.05). And the average of corneal astigmatism was(0.89±0.63)D and(1.71±1.16)D before and three months after the operation respectively with6.0mm small incision.There was significant difference after surgery (t=-4.062, P=0.000).But no significant difference between WTR and ATR group. And the percentage of astigmatism with the rule decreased from40.4%to32.6%after the surgery, reversely, the percentage of ATR increased from48.9%to53.5%(2.2mm). the percentage of astigmatism with the rule decreased from49.0%to2.6%after the surgery, reversely, the percentage of ATR increased from49.0%to89.5%(6.0mm).Three months after the operation,the surgically induced astigmatism was (1.27±1.06) D,(0.74±0.86) D in WTR group,(1.21±0.81) D in ATR group.Conclusion Surgically induced astigmatism is very small after a2.2mm superior corneal incision in phacoemulsification without suture. And the corneal astigmatism shifts from with-the-rule to against-the-rule astigmatism after surgery.Part three1.8mm coaxial micro-incision cataract surgery and3.0mm standard phacoemulsification:Prospective Comparative StudyObjective To compare the effects of1.8mm coaxial micro-incision cataract surgery and3.0mm standard phacoemulsification cataract surgery and assess the potential advantages of the former over the latter.Methods In a controlled prospective clinical trial,39eyes of37patients with cataract of grade2to4on the Lens Opacities Classification System III had phacoemulsification.23eyes of22patients were randomized to have coaxial micro-incision cataract surgery and16eyes of15patients by the standard phacoemulsification. All surgeries were performed by the same surgeon using the same machine (Stelleris).Intraoperative parameters were average ultrasound power (AVE), effective phacoemulsification time (EPT) and final size of the corneal incision. Postoperative parameters were visual acuity, surgery induced astigmatism (SIA), corneal thickness, fovea thickness, endothelial cell count, and presence of flare and cells in the anterior chamber at intervals of1day,l week,1month and3months after surgery.Results The statistically significant difference between the2groups was the AVE(t=-2.17, P=0.037), but no significant difference on EPT (P>0.05). One day post operation, the1.8mm group showed better uncorrected distance visual acuity (UDVA) and best corrected visual acuity (BCVA) as compared to pre operation. The difference was statistically significant(t=-2.70、t=-2.31, P=0.010、P=0.026).While the3.0mm group showed better UDVA but not BCVA as compared to pre operation (t=-2.26、-1.50, P=0.032、0.146).One week after the surgery,visual acuity rapidly promote on1.8mm group while slowly on3.0mm.The1.8mm group showed better UDVA as compared to the3.0mm group,the difference was statistically significant (t=-2.01, P=0.046). There were no significant differences between these two groups one day, one month and three month post operation. Visual acuity becomes stable3months after the surgery. Analysis the SIA in two area, SIA in center of cornea3mm and5mm were (-0.69±0.26)D,(-0.51±0.2)D in the1.8mm group, and(-1.34±0.64)D,(-0.83±0.46)D in the3.0mm group, respectively,1week after the surgery. The differences between the two groups were statistically significant (t=-2.98, P=0.008),(t=-2.19, P=0.039). SIA decreased significantly in1.8mm group while tardily in the3.0mm group.SIA become stable3months after the surgery in both groups. There were no significant differences on endothelial cell density, anterior chamber depth, fovea thickness and cornea thickness between these two groups.Conclusion coaxial1.8mm microincision Phacoemulsiflcation is a safe and effective technique for cataract surgery.