The Effects of Cheap Tinted Contact Lenses on Corneal Swelling and Ocular Surface Inflammation

PURPOSE: To evaluate the effects of cheap tinted contact lenses on corneal swelling and ocular surface inflammation, compared to hydrogel and silicone hydrogel contact lenses. METHODS: Forty eyes of 20 New Zealand white rabbits were randomly assigned to 4 groups. Two types of tinted contact lenses, hydrogel lenses, and silicone hydrogel lenses were each applied to 10 rabbit eyes. Corneal thickness and tear lactate dehydrogenase (LDH) activity were measured at 1 and 4 days after contact lens wear, and the inflammation of ocular surface was scored at 4 days after contact lens wear. The internal surface of the cheap tinted lens was examined with a scanning electron microscope to compare the surface quality between the tinted and non-tinted area. RESULTS: Although the corneal swelling of the silicone hydrogel lens group was significantly lower than the other 3 lens groups after contact lens wear (p0.1). Tear LDH activity at 1 and 4 days after contact lens wear showed no significant difference among the 4 groups (p>0.29). The scores of ocular surface inflammation in the 2 tinted contact lens groups were greater than the hydrogel and silicone hydrogel lens groups (p=0.03). The scanning electron microscope revealed the internal surface of the tinted area in the tinted contact lens was coarse and irregular though the surface of the non-tinted area was relatively smooth. CONCLUSIONS: Regarding corneal swelling and tear LDH activity, the cheap tinted contact lenses used in Korea were not significantly different from the common hydrogel contact lenses. However, tinted contact lenses showed a greater tendency to provoke ocular surface inflammation than other lenses. The coarse and irregular surface of the tinted area in the tinted contact lens appears to play a role in provoking severe ocular surface inflammation.

Comparison of the Phaco Chop and the Mini Chop Methods in Cataract Surgery

PURPOSE: To compare effective phacoemulsification time (EPT), the severity of corneal swelling and corneal endothelial cell density after cataract surgery between the phaco chop method and the mini chop method. METHODS: Cataract surgery was performed by phaco chop (15 eyes) or by mini chop (13 eyes) method in 28 eyes of 27 patients. The nuclear opacity of cataract grade was more than 5 on LOCS (Lens opacities classification system) III. EPT and the amount of irrigated BSS solution were measured during the operation. Corneal thickness (preoperative, immediate postoperative, postoperative 1 day, 1 week, 1 month, and 3 months) and corneal endothelial cell density (preoperative, postoperative 1month and 3 months) were measured. RESULTS: The EPT of phaco chop group was 5.2 sec and that of mini chop was 1.0 sec (p=0.000). The amount of irrigated BSS was 193.7 ml and 170.4 ml in the phaco chop group and the mini chop group, respectively. The increase in corneal thickness was 3.2% and 0.9% at immediately after surgery (p=0.128), 19.0% and 10.5% at postoperative 1 day (p=0.088), 5.7% and 1.5% at postoperative 1 week (p=0.080), 0% and -1.3% at postoperative 1 month (p=0.717), and -0.4% and -0.6% at postoperative 3 months (p=0.890) in the phaco chop group and the mini chop group, respectively. Corneal endothelial cell density decreased 23.0% in the phaco chop group and 9.4% in the mini chop group at postoperative 1 month (p=0.005) and 22.9%, 12.6%, at 3 months respectively (p=0.036). CONCLUSIONS: The mini chop technique reduced permanent endothelial cell damage in comparison with the phaco chop method and might be more effective in decreasing corneal swelling during the early postoperative period than the phaco chop method.

The Effect of Antibiotics in the Irrigation Solution on Corneal Endothelial Function

The practice of adding antibiotics to anterior chamber-irrigating solutions as a prophylaxis for endophthalmitis has been used recently.To evaluate corneal endothelial toxicity of different concentrations of antibiotics in irrigating solutions, rabbit corneas were mounted in the in-vitro dual-cham-bered specular microscope and the endothelium was perfused with glu-tathione-bicarbonate Ringer solution (GBR)containing antibiotics such as ofloxacin, vancomycin or cephapirin.Mate corneas were perfused with GBR alone and used as control.Corneal thickness was measured every 15 minutes throughout the perfusion period and corneal swelling rates were calculated. Swelling rates of corneas perfused with 2 /ml or 5 /ml ofloxacin, 60 microgram/ml or1 0 /ml vancomycin, and 10 /ml or 20 /ml cephapirin was not significantly different from that of control (p>0.05).The corneas perfused with 20 /ml cephapirin deswelled probably due to high osmolarity of it.Perfusion with 10 /ml vancomycin plus 5 /ml ofloxacin did not show corneal swelling compared to control (p>0.05).This study demonstrates that the above concentra-tions of antibiotics in irrigating solutions do not affect endothelial function of the rabbit cornea.

Effect of Ascorbic Acid on Corneal Endothelial Function

It has been reported that ascorbic acid[AA]appears to be actively taken up by the corneal endothelium and protect the endothelium against harmful effects of the oxidative reactions. To investigate the effect of ascorbic acidon the corneal endothelial function, rabbit`s corneas were mounted in the in vitro specular microscope. Corneal endothelium was perfused with ascorbic acid, then switched to AA plus ouabain solution, and vice versa. Also, phloretin was perfused onto the endothelium with AA and ouabain. Andcorneal endothelium was perfused with GBR or AA solution followed by perfusion with ouabain. Corneal thickness was measured during the perfusion and the corneal swelling rate calculated. Corneal endothelial permeability was also measured after perfusion of ascorbic acid. Perfusion with AA showed no corneal swelling, but swelling rate was even lower than GBR control. Corneal endothelial permeability did not change upon AA perfusion. In corneas preperfused with ouabain, AA added to ouabain solution decreased corneal swelling rates induced by ouabain solution[19.9 vs. 40.5 micrometer/hr]. The corneas preperfused with AA also showed decreased swelling rates with subsequent perfusion of ouabain added to AA solution[21.7 vs.28.6 micrometer/ hr]. Phloretin inhibited the effect of AA.However, when ouabain was removed, the corneal swelling plateaued but did not return to baseline thickness in both AA and GBR perfusion.The results of this study showed that AA can increase corneal endothelial pump function and reduce corneal swelling caused by ouabain.

The Effect of Mitomycin-C on the Function of Corneal Endothelial Cells in Rabbit

The purpose of this study is to investigate the toxicity of mitomycin-C[MMC]to the corneal endothelial cells, which is medical adjunct to pterygium and glaucoma surgery.Rabbit corneas were mounted in the in-vitro dual-chambered specular microscope.Corneal endothelium was perfused with the glutathione-bicarbonate-Ringer[GBR]solution for one hour, then, perfused with 0.02%, 0.01%, and 0.005%MMC in GBR solution in experimental groups, and with GBR solution only in control group.Corneal thickness was measured every 15 minutes during perfusion and corneal swelling rate was calculated.Corneal endothelial permeability was also measured in another experiment.In MMC-mixed group, the early swelling rate decreased due to osmolarity of MMC, but after removal of MMC, the swelling rate increased compared to that of the control group.The pattern of increase was not a linear form, but a secondary curve with the plateau. In 0.02%and 0.01%MMC group, corneas swelled significantly, but not in 0.005%group.Corneal endothelial permeability was 4.21 +/-0.50 x10-4cm/min at 0.005%MMC, 4.10 +/-0.93 x10-4cm/min in control, and 4.25 +/-0.48 x10-4cm/min at 0.01% MMC, 3.73 +/-0.73 x10-4cm/min in control. No significant changes in permeability was observed.In conclusion, MMC of 0.01% or higher exposed to corneal endothelial cells induced corneal swelling of which mechanism was thought to be due to inhibition of Na/K-ATPase by MMC.

The Effect of Fluorescein and Indocyanine Green on Corneal Endothelial Function

Both sodium fluorescein[FL] and indocyanine green[ICG] were used for fundus angiography. Recently, these were also used during cataract surgery for enhancement of capsular visualization in white mature or hypermature cataract. So, ICG and FL may influence corneal endothelial function if left in anterior chamber. To evaluate the effect of intracameral FL or ICG on corneal endothelial function, rabbit corneas were isolated &mounted in the in-vitro specular microscope for endothelial perfusion. Experimental corneas were perfused with different concentrations of FL or ICG. Control corneas were perfused with glutathione-bicarbonate Ringer solution[GBR]. Corneal thickness was measured every 15 minutes during the perfusion and corneal swelling rates were calculated. Corneal endothelial permeability[Pa c] was measured according to the method of Watsky et al. The corneas perfused with FL, 2.5% deswelled probably due to high osmolarity. Swelling rates of corneas perfused with 1% and 0.5% FL did not differ significantly from control[p>0.05]. The corneas perfused with 0.01%, 0.005%, 0.002%, and 0.001% ICG swelled significantly[p0.05]. Pa c in corneas perfused with ICG, 0.005% increased markedly compared to control while corneas perfused with FL, 1% showed decreased permeability. The results of this study showed that FL did not affect endothelial function of rabbit cornea in relatively high concentrations while ICG affected endothelial function even in lower concentrations. With respect to clinical use of intracameral ICG, close attention must be paid.

The Changes of Ultrastructure and Function of the Corneal Endothelial Cell Caused by Benzalkonium Chloride

The purpose of this study was to evaluate alterations in corneal endothelial cell function and ultrastructure caused by benzalkonium chloride (BAC). Sixteen albino rabbits (32 eyes)were used for this study. One cornea of each matched pair was assigned to experimental group and the other cornea to control group. The experimental groups were divided into 4 groups, of which corneal endothelium were perfused with 0.01%, 0.001%, 0.0002%, and 0.0001% BAC. After paired rabbit corneas were isolated and mounted in the in vitro dual-chambered specular microscope, experimental corneas of each matched pair were perfused with different concentrations of BAC. Control corneas were perfused with glutathione-bicarbonate-Ringer solution(GBR). Corneal thickness was measured every 15 minutes throughout the perfusion period.Swelling rates were calculated by linear regression analysis, and compared to swelling rate of each paired mate perfused with GBR alone. At the end of perfusion,the corneas were fixed in 2.5%glutaraldehyde solution for transmission electron microscopy(TEM). Swelling rates of rabbit corneas perfused with BAC, 0.0001% did not differ significantly from control corneas (p>0.05). But, 0.0002%, 0.001%, and 0.01% BAC differed significantly from control corneas (p<0.05). BAC, 0.0001% showed normal corneal endothelial findings, but 0.0002% and 0.001% BAC showed reversible endothelial cellular injury. BAC, 0.01% showed irreversible endothelial cellular injury such as loss of nuclear membrane and disruption of cellular organelles. The results of this study indicate that long-term use of topical eye solutions containing BAC might induce corneal endothelial damage, especially in the absence of epithelial barrier such as corneal ulcer.

Experimental 24 Hour Corneal Swelling by Extended Wear Contact Lenses

We evaluated corneal swelling induced by extended wear contact lenses(EWCLs) in New Zealand white rabbits domestically available in Korea. At first, we measured the corneal thickness prior to contact lens wearing with ultrasonic pachometer and examined the condition of the anterior segment of the eye. Then four soft EWCLs, one rigid gas permeable lens, and one disposable lens were applied on the corneas of the rabbits for 24 hours in closed eye condition achieved by transient tarsorrhapy. After 24 hours, the corneal thickness was remeasured and the condition of the external eye was reexamined to compare with the initial values. Conclusively, corneal swelling was developed after 24hour wearing of EWCLs in all rabbits. The percent corneal thickness changes decreased inthe following order; Ciba soft(Cooper Vision) 27.54%. Hyper II(International Contact Lens Lab.) 21.99%, Bescon III(International Contact Lens Lab.) 16.15%, Ciba thin(Cooper Vision) 14.22%, Optima FW(Bash and Lomb) 13.79%, Acuvue(Johnson and Johnson). The control group whitch did not wear any contact lens showed no change in the corneal thickness(p>0.05). The results of corneal swelling correlated well with the DK/L of each EWCLs. This experiment revealed that the EWCLs used widly in Korea could induce corneal swelling and so careful evaluation 0f the EWCLs wearers may be required.