Staining Composition with Improved Staining Intensity

Abstract

A staining composition is provided with improved staining intensity. The composition comprises a vital dye and hyaluronic acid, wherein the vital dye comprises Chicago Sky Blue and Trypan Blue. The staining composition is used to stain the lens capsule during cataract surgery and provides sufficient contrast such that no air bubble needs to be injected in the anterior chamber during cataract surgery.

Claims

1. A staining composition comprising a vital dye and hyaluronic acid, wherein the vital dye comprises Chicago Sky Blue and Trypan Blue.

2. The staining composition of claim 1, wherein the hyaluronic acid is present in an amount less than 0.8 wt. %, based on the total weight of the staining composition.

3. The staining composition of claim 1, wherein the weight ratio of Trypan Blue to Chicago Sky Blue is between 1:3 and 3:1.

4. The staining composition according to claim 1, wherein the weight ratio of Trypan Blue to Chicago Sky Blue is 2:1 or less.

5. The staining composition according to claim 1, wherein the weight ratio of Trypan Blue to Chicago Sky Blue is 1:1 or more.

6. The staining composition according to claim 1, wherein the combined Trypan Blue and Chicago Sky Blue concentration in the staining composition is 0.02-0.2 wt. %.

7. The staining composition according to claim 1, wherein the combined Trypan Blue and Chicago Sky Blue concentration in the staining composition is 0.04-0.1 wt. %.

8. The staining composition according to claim 1, wherein the composition comprises 0.2-0.75 wt. % hyaluronic acid.

9. The staining composition according to claim 1, wherein the hyaluronic acid has a molecular weight of between 100,000 to 5,000,000 Da.

10. The staining composition according to claim 1, wherein the dye further comprises a compound selected from the group consisting of methylene blue (MB), brilliant blue G (BBG), brilliant blue R (BBR), patent blue V, trypan red, brilliant crysyl blue, indocyanine green, light green SF yellowish (LG), phenol red, chlorophenol red-beta-D-galactopyranoside (CPRG), rose bengal (4,5,6,7-tetrachloro-2,4,5,7-tetraiodofluorescein), phloxine B and safranin.

11. A method of ocular surgery, which method comprises staining an ocular tissue or part thereof with the staining composition of claim 1 and performing surgery on the stained ocular tissue or its surrounding tissue.

12. The method of claim 11, wherein the ocular surgery is cataract surgery, and wherein the method comprises staining the lens capsule with the staining composition and subsequently removing of the lens.

13. The method of claim 12, wherein the lens capsule is to be stained by applying the staining composition to the outer surface of the lens capsule.

14. The method of claim 12, wherein the cataract surgery comprises the steps of opening the anterior chamber of the eye; and optionally injecting an air bubble in the anterior chamber; and optionally injecting a viscoelastic liquid in the anterior chamber; and staining the lens capsule; and creating an opening in the lens capsule; and removing the lens from the lens capsule, while leaving the lens capsule sufficiently intact; and placing a synthetic lens in the lens capsule.

15. The method of claim 12, wherein no air bubble is injected into the anterior chamber during the surgery.

16. A method of staining an ocular tissue or part thereof comprising applying the staining composition of claim 1 to the ocular tissue or part thereof.

Description

EXAMPLE 1

Effect of Dye Combinations on Staining

[0075] Eight staining solutions were prepared with different dye combinations of Trypan Blue (TB), Chicago Sky Blue (CSB), Brilliant Blue G (BBG) and Methylene Blue (MB). The specific dye combinations and concentrations used are listed in Table 1. The amounts listed in Table 1 represent the weight amount of the dye in grams that is present in 100 mL staining solution (w/v %). Although the total dye concentration varied for the different solutions, the absorbance at the wavelength maximum (A.sub.max) was comparable for each staining solution.

TABLE-US-00001 TABLE 1 composition staining solutions Example 1 staining dye solution: A B C D E F G H I J TB 0.06 0.1 0.033 0.066 0.05 0.033 0.033 (w/v %) CSB 0.1 0.066 0.033 0.05 0.066 0.066 (w/v %) BBG 0.095 0.033 (w/v %) MB 0.024 0.01 (w/v %)

[0076] Forty pairs of porcine cadaveric eyes were obtained less than six hours post mortem. The age of the animals was approximately six months, and lens capsules were isolated within 8 hours after death. First, debris like muscle, fat and other tissue were removed from the globe. Next, a 17.0 min corneo-scleral rim was excised from each globe, and immediately after excision of the corneo-scleral rim, the lens capsule was harvested by grasping the iris root with a forceps, separating the vitreous from the iris and lens with a surgical blade, and peeling the lens, including the iris, from the vitreous. The lens (including the iris) was stored in NaCl at room temperature until use.

[0077] Per staining solution, four porcine lens capsules were stained by immersing the lens capsule (including iris) in 2-5 ml dye solution for 10 s and washing it with PBS subsequently. For digital imaging (Casio Exilim EX-Z40, China), the stained lens, including iris, were placed in a glass bowl and photographs were made.

[0078] The intensity of staining was scored on a scale 1 to 5. The staining obtained by solution A was used as the standard and set to a score of 3. A score of 1 was used to indicate a staining much worse than solution A, a score of 2 was used to indicate a staining worse than solution A, a score of 3 was used to indicate a staining comparable to solution A, a score of 4 was used to indicate a staining better than solution A and a score of 5 was used to indicate a staining much better than solution A.

TABLE-US-00002 TABLE 2 staining test scores for staining porcine lens capsule (n = 4) staining dye solution: A B C D E F G H I J capsule 1 3 3 3 4 1 1 3 1 3 2 capsule 2 3 3 3 3 5 5 3 1 3 2 capsule 3 3 3 3 4 5 5 3 1 3 2 capsule 4 3 3 3 4 5 5 4 1 4 2 Average: 3 3 3 4 4 4 3 1 3 2

[0079] Staining the lens capsule with solutions D, E and F (dye combination TB+CSB) resulted in the most intense staining. These solutions scored better on staining than solutions A and B, which contained a single dye, riz. TB.

[0080] Staining the lens capsules with solutions H and J (dye combinations TB+MB and CSB+MB) resulted in a much less intense staining compared to the other solutions.

[0081] Staining the lens capsules with solution G (dye combination TB+BBG) resulted in a staining intensity comparable to the single dye solutions with TB (solutions A and B).

[0082] From this example, it can be concluded that the combination of TB and CSB results in a superior staining intensity compared to the other dye combinations tested.

EXAMPLE 2

Synergetic Effect TB+CSB in the Absence of HA

[0083] In view of the results of increased staining for the dye combination TB+CSB, an absorbance test was conducted to quantify this effect. It is hypothesized that TB and CSB interact with each other on a molecular level in solution, thereby influencing the absorbance maximum and intensity.

[0084] Solutions of TB, CSB and TB+CSB were prepared (samples 1-3). The samples were prepared as follows.

[0085] For sample 1, an amount of 25.33 M of TB was dissolved in 1 mL phosphate buffered saline.

[0086] For sample 2, an amount of 32.87 M of CSB was dissolved in 1 mL phosphate buffered saline.

[0087] For sample 3, an amount of 12.67 M TB and 16.44 M of CSB were dissolved in 1 mL phosphate buffered saline. Thus, the amount of TB and CSB used in sample 3 were half those used in samples 1 and 2.

[0088] Each solution was put in a cuvette and absorbance was measured using a spectrophotometer. Furthermore, a theoretical combined absorbance was determined by calculating the sum of the absorbances of 12.67 M TB and 16.44 M CSB using the relation between the absorbance and the concentration as measured in sample 1 and sample 2.

[0089] The results are shown in FIG. 1. FIG. 1 shows the three absorbance spectra measured for samples 1-3 (TB=continuous line; CSB=dotted line; physical mixture TB/CSB=bold dotted line), as well as the absorbance calculated by taking the sum of half the absorbance measured for sample 1 and half the absorbance measured for sample 2 (represented by the bold continuous line in FIG. 1).

[0090] From FIG. 1, two effects can be observed on the absorbance. First, FIG. 1 shows that the absorbance measured in the 500-610 nm region for sample 3 (TB/CSB mixture) was higher than the absorbance in the 500-610 nm region calculated from the absorbance measurements of samples 1 and 2 (sum of TB and CSB individually). Second, a shift in wavelength was observed for the maximum absorbance, such that the maximum occurred at a lower wavelength. The specific wavelength region wherein these changes occur correspond to the sensitive wavelength region in the eye. The human eye is most sensitive at a wavelength of 555 nm. Accordingly, both the increase in absorbance in the 500-600 region, as well as the shift in wavelength towards a lower value, are expected to contribute to an improved sensitivity in the eye toward the dye combination. Accordingly, it follows that the combination of TB+CSB shows better absorbance properties than could have been expected based on the individual absorbances measured for CSB and HA. It is hypothesized that this synergetic effect is the reason that the dye combination TB+CSB is perceived as having an increased intensity compared to TB or CSB alone.

[0091] Subsequently, the effect of gelatin was measured. A fourth sample was prepared similar to sample 3, except that 5 mg/ml gelatin was added as an additional compound to the sample (sample 4). Gelatin is a hydrolyzed collagen and was used to simulate the presence of collagen molecules in ocular tissue. As the dye will bind to the gelatin, this experiment simulates the binding of the dye to ocular tissue.

[0092] An absorbance spectrum was obtained for sample 4 that was similar in shape to the TB/CSB mixture (sample 3) in FIG. 1.

[0093] FIG. 2 shows the effect of gelatin on the absorbance of the dye combination TB+CSB. The two graphs in FIG. 2 represent difference spectra that were calculated from the absorbance spectrum of sample 4. The continuous line in

[0094] FIG. 2 was obtained by subtracting the absorbance spectrum obtained for sample 3 (physical mixture, no gelatin) from the absorbance spectrum obtained for sample 4 (physical mixture, gelatin). The dotted line in FIG. 2 was obtained by subtracting the theoretical combined absorbance spectrum calculated from samples 1 and 2 (calculated sum, no gelatin) from the absorbance spectrum obtained for sample 4 (physical mixture, gelatin).

[0095] It can be concluded from FIG. 2 that the presence of gelatin has a positive effect on the absorbance of the dye combination TB+CSB. Thus, the staining intensity of the dye combination TB+CSB is even stronger when applied to the eye tissue than in a liquid solution of TB+CSB.

EXAMPLE 3

Synergetic Effect TB+CSB in the Presence of HA

[0096] Example 2 was repeated with samples comprising hyaluronic acid (HA), in order to show that the synergetic effect observed for the dye combination TB and CSB also occurs in the presence of HA.

[0097] Solutions of TB, CSB and TB+CSB were prepared (samples 5-7). The samples were prepared as follows.

[0098] For sample 5, an amount of 32.85 M of TB and 5 mg gelatin were dissolved in 1 mL phosphate buffered saline.

[0099] For sample 6, an amount of 36.53 M of CSB and 5 mg gelatin was dissolved in 1 mL phosphate buffered saline.

[0100] For sample 7, an amount of 15.31 M TB and 18.05 M of CSB were dissolved in 1 mL phosphate buffered saline. Thus, the amount of TB and CSB used in sample 7 were about half those used in samples 5 and 6.

[0101] Furthermore, an amount of hyaluronic acid was dissolved in each sample such that it contained a 0.34 wt. % solution of HA. Each sample also contained 5 mg/ml gelatin.

[0102] Each solution was put in a cuvette and absorbance was measured using a spectrophotometer. Furthermore, a theoretical combined absorbance was determined by calculating the sum of the absorbances of 15.31 M TB and 18.05 M CSB using the relation between the absorbance and the concentration as measured in sample 5 and sample 6.

[0103] The results are shown in FIG. 3. FIG. 3 shows the three absorbance spectra measured for samples 5-7 (TB+HA=continuous line; CSB+HA=dotted line; physical mixture TB+CSB+HA=bold dotted line), as well as the theoretical combined absorbance (calculated sumrepresented by the bold continuous line in FIG. 3). The theoretical combined absorbance was calculated by taking the sum of the absorbance of 15.31 M TB using the molar absorbance coefficient of TB (as determined from the measured absorbance and known concentration in sample 5) and the absorbance of 18.05 M CSB using the molar absorbance coefficient of CSB (as determined from the measured absorbance and known concentration of CSB in sample 6).

[0104] First, FIG. 3 shows that the absorbance in the 500-610 nm region was higher for sample 7 (TB/CSB mixture) than the absorbance in the 550-610 nm region calculated from the absorbance measurements of samples 5 and 6 (sum of TB and CSB individually). The specific wavelength region for which the absorbance is increased corresponds to the sensitive wavelength region in the eye. Therefore, the increase in intensity in this region is expected to result in an increase in perceived intensity.

[0105] Second, a shift in wavelength was observed for the maximum absorbance, such that the maximum occurred at a lower wavelength. The human eye is most sensitive at a wavelength of 555 nm. Accordingly, the shift in maximum towards a value closer to a wavelength of 555 nm is expected to result in an increase in perceived intensity.

[0106] Accordingly, it follows that the combination of TB+CSB shows better absorbance properties than could have been expected based on the individual absorbances measured for CSB and HA. It is hypothesized that this synergetic effect is the reason that the dye combination TB+CSB is perceived as having an increased intensity compared to TB or CSB alone.

EXAMPLE 4

Effect of Polymers on Staining Intensity

[0107] The effect of polymer type on staining was determined by staining human lens capsules with various staining solutions comprising different types and amounts of polymer.

[0108] Ten different staining solutions were made comprising TB in an amount of 0.033 g/100 mL and CSB in an amount of 0.066 g/100 mL. Furthermore, nine of these staining solutions comprise one of the following polymers: [0109] polyethylene glycol (PEG) with an average M.sub.w of 3350 Da [0110] polyethylene glycol (PEG) with an average M.sub.w of 35000 Da [0111] hyaluronic acid (HA) with a M.sub.w of 1200-2000 kDa [0112] hydroxypropyl methylcellulose (HPMC) with a M.sub.w of 86,000 [0113] polyvinylpyrrolidone (PVP with a M.sub.w of 10,000
The specific composition of the staining solutions are listed in Table 3.

TABLE-US-00003 TABLE 3 staining solution compositions polymer concentration Solution polymer (w/v %) dye 1 PEG 3350 4 TB + CSB 2 PEG 3350 20 TB + CSB 3 PEG 35000 4 TB + CSB 4 PEG 35000 20 TB + CSB 5 HA 0.4 TB + CSB 6 HA 0.65 TB + CSB 7 HA 0.8 TB + CSB 8 HPMC 1 TB + CSB 9 PVP 4 TB + CSB 10 none TB + CSB

[0114] Twenty human cadaver eyes from twenty donors (mean donor age 74+10 years; range, 48-85 years) were used for this experiment. The donor globes were decontaminated and followed by corneal graft preparation with excision of the corneoscleral rims. The eyes were stored in saline solution (NaCl 0.9%) at 4-6 C. for 4-20 days. The lens capsule was harvested by cutting the sclera radially at four places (at 90 apart) in order to open the globe. A circumferential cut was performed to the ciliary body over 360. The tissue containing the iris, the ciliary body and the lens was pulled out with a forceps and separated from the vitreous (if necessary, the scissors were used to cut the vitreous attached to the posterior lens capsule). The intact lens (containing its capsule) was then obtained, and the surrounding tissues (iris and ciliary body) were gently removed with two forceps.

[0115] Per staining solution, two human lens capsules were stained by immersing the lens in 2-5 ml dye solution for 10-15s followed by rinsing with H.sub.2O. Longer staining times (20-30 s) were used in case the staining solution was especially viscous (0.65% HA, 0.8% HA, 20% PEG 3350 and 20% PEG 35000). To evaluate the staining efficiency the lenses were placed in a petri dish, photographed, visually and biomicroscopically inspected and scored.

[0116] The intensity of staining was scored on a scale of 1 to 5 and was based on visual inspection of the lens capsules and represented different staining intensities:

[0117] 1. uncolored; comparable to native lens color;

[0118] 2. some staining

[0119] 3. good staining

[0120] 4. very good staining

[0121] 5. excellent staining

The results are shown in Table 4.

TABLE-US-00004 TABLE 4 staining test scores for staining human lens capsule (n = 2) staining solution 1 2 3 4 5 6 7 8 9 10 capsule 1 3 2 2 2 4 5 3 2 2 4 capsule 2 2 2 1 5 5 3 1 3 average 2.5 2 1.5 2 4.5 5 3 2 1.5 3.5

[0122] During staining in 0.65% HA solution (Solution 6), one of the lens capsules ruptured and during the washing step it became completely detached from the lens. However, no subsequent staining of the lens itself was observed. This unintended event confirms that the staining solution selectively stained the lens capsule and not the underlying lens.

[0123] The most intense staining was obtained using Solution 5 (0.4% HA) and Solution 6 (0.65% HA). The higher concentration of HA (0.8%) in Solution 7 made the solution extremely viscous and difficult to handle; the lens did not submerge into the staining solution by itself and more manipulation was needed to uniformly cover the dye. The eventual staining obtained was poor.

[0124] All four staining solutions with PEG (Solutions 1-4) resulted in considerably less intense staining than the staining solutions with HA. Staining with Solution 8 (1% HPMC) and Solution 9 (4% PVP) showed very poor results. It is hypothesized that these polymers inhibit staining to some degree, probably by competing either for binding to the dyes or to the binding sites of the proteins.

[0125] It can be concluded that staining solutions comprising TB, CSB and HA are able to provide an increased staining intensity to the human lens capsule compared to staining solutions comprising TB, CSB and a different polymer, such as PEG, HPMC or PVP.

EXAMPLE 5

Absorbance Tests on Polymer Effect on Staining Intensity TB+CSB

[0126] In view of the results of the staining behavior for the dye-polymer combinations tested in Example 4, an absorbance test was conducted to quantify the effect of the polymer. This example shows the effect of different polymers on the absorbance of the dye combination TB+CSB, as well as the effect of gelatin (which resembles collagen present in ocular tissue).

[0127] The absorbance spectra of solutions of TB+CSB with one of HA, PEG and HPMC was measured (samples B, C and D) and compared with the absorbance spectrum of a solution of TB+CSB without polymer (sample A) and the absorbance spectrum calculated by taking the average sum of the absorbance measured for TB and CSB individually (described in Example 2 and 3 above).

[0128] Four samples were prepared. All samples contained a solution of TB and CSB dissolved in a phosphate buffer (PBS), using similar concentration as were used in Example 2 and 3. Further, each sample contained 5 mg gelatin per ml sample solution. The samples were different from each other in the amount and type of polymer present: [0129] sample A (reference): no polymer [0130] sample B: hyaluronic acid (0.34 wt. %) [0131] sample C: HPMC (0.36 wt. %) [0132] sample D: PEG 3350 (1.84 wt. %)

[0133] The absorbance of these four samples was measured. The absorbance spectra of these samples is not shown, but are similar in shape as those depicted in FIG. 1. The results of the absorbance measurements is depicted in FIGS. 4-6.

[0134] FIG. 4 shows the effect of polymer on the absorbance of the dye combination TB+CSB in the presence of gelatin. For each of samples A-D, a difference spectrum was calculated by subtracting the absorbance spectrum obtained for sample 3 (physical mixture, no gelatin) from the absorbance spectrum measured for samples A-D. These four difference spectra are depicted in FIG. 5.

[0135] From FIG. 4 it can be concluded that hyaluronic acid has a positive effect on the absorbance of the dye combination TB+CSB, whereas both HPMC and PEG3350 have a negative effect. This explains the reduced staining intensity observed in Example 4.

[0136] FIG. 5 shows the effect of gelatin on the absorbance of the dye combination TB+CSB. The continuous line in FIG. 5 was obtained by subtracting the absorbance spectrum obtained for sample 3 (physical mixture, no gelatin) from the absorbance spectrum obtained for sample A (reference, gelatin). The dotted line in FIG. 5 was obtained by subtracting the theoretic combined absorbance spectrum calculated from samples 1 and 2 (HA, no gelatin) from the absorbance spectrum obtained for sample A (reference, gelatin).

[0137] It can be concluded from FIG. 5 that the presence of gelatin has a positive effect on the absorbance of the dye combination TB+CSB. Thus, the staining intensity of the dye combination TB+CSB is even stronger when applied to the eye tissue than in a liquid solution of TB+CSB.

[0138] FIG. 6 shows the effect of HA on the absorbance of the dye combination TB+CSB. The continuous line in FIG. 6 was obtained by subtracting the absorbance spectrum obtained for sample 3 (physical mixture, no gelatin) from the absorbance spectrum obtained for sample B (HA, gelatin). The dotted line in FIG. 5 was obtained by subtracting the theoretic combined absorbance spectrum calculated from samples 1 and 2 (no gelatin) from the absorbance spectrum obtained for sample B (HA, gelatin).

[0139] It can be concluded from FIG. 6 that the presence of HA and gelatin together has a positive effect on the absorbance of the dye combination TB+CSB. Thus, the staining intensity of the composition according to the invention is even stronger when applied to the eye tissue than in the liquid composition itself.

[0140] When comparing FIGS. 5 and 6, it can be observed that the increase in absorbance (compared to the calculated combined TB+CSB absorbance) is higher in FIG. 6 than it is in FIG. 5, especially at the maximum. The absorbance maximum of the continuous line for sample B in FIG. 6 (668 nm, absorbance 0.08639) is significantly higher than the absorbance maximum of the continuous line for sample A in FIG. 5 (665 nm, absorbance 0.0725). Accordingly, it can be concluded that the presence of HA has a positive effect on the absorbance of the dye combination TB+CSB.

[0141] Summarizing, this Example shows that the staining intensity of the dye combination TB+CSB is increased by the presence of hyaluronic acid. This is surprising, as other polymers such as PEG and HPMC have a negative effect. Further, it can be concluded that the dye combination has an improved staining intensity when contacted with eye tissue (as simulated by gelatin).

EXAMPLE 6

Clinical Study in Cataract Surgery

[0142] A clinical test was conducted to evaluate the staining capacity of staining solutions comprising a dye combination of Trypan Blue (TB), Chicago Sky Blue (CSB) and hyaluronic acid (HA) on human lens capsules. Different concentrations of TB, CSB and HA were used and the staining intensity and duration of the dye solution evaluated.

[0143] All samples were based on a neutral isotonic phosphate buffered solution comprising water (1 L), NaCl (8.2 g), Na.sub.2HPO.sub.4.2H.sub.2O (1.9 g) and NaH.sub.2PO.sub.4.2H.sub.2) (0.3 g) and having a pH between 7.3 and 7.45 and an osmolality in the range of 257-314 mOsm/kg. The concentration of TB, CSB and HA of the different samples is shown in Table 5. The molecular weight of HA was in the range of 1200-2000 kDa. The amounts are given in weight percentage and are based on the total weight of the staining solution.

TABLE-US-00005 TABLE 5 staining compositions used in clinical tests Trypan Blue Chicago Sky Blue Hyaluronic Acid Concentration Concentration Concentration (wt. %) (wt. %) (wt. %) Sample A 0.033 0.066 0.55 Sample B 0.033 0.066 0.60 Sample C 0.033 0.066 0.65 Sample D 0.033 0.066 0.70 Sample E 0.033 0.066 0.75 Sample F 0.033 0.066 0.80 Sample G 0.020 0.040 0.65 Sample H 0.06 0 0

[0144] The different samples were clinically tested by three different surgeons. The surgeons applied the samples as a staining composition to stain the human lens capsule during cataract surgery. Sample H corresponded to the staining solution that was used at the time by the surgeons in cataract surgery.

[0145] The cataract surgery either made use of extracapsular cataract extraction or phacoemulsification. The staining solution was gently applied to the frontal lens capsule using a blunt cannula. No air bubble was injected in the anterior chamber during surgery. The anterior chamber was subsequently irrigated in order to remove any excess dye.

[0146] The parameters that were evaluated by the surgeons were the staining intensity (poor/average/good/excellent), duration of the staining effect (poor/average/good/excellent), and the injectability, i.e. ease of the injection (poor/average/good/excellent). The results are shown in Table 6.

TABLE-US-00006 TABLE 6 overview of clinical results Staining intensity Duration of staining Injectability Sample A Good Poor Excellent Sample B Good Average Good Sample C Good Good Good Sample D Good Good Poor Sample E Good Good Poor Sample F Good Good Poor Sample G Poor Poor Poor Sample H Average Poor Excellent

[0147] It can be concluded from the clinical evaluation that the staining compositions according to the invention have better staining intensity and improved duration of staining compared to the staining composition currently used in the art (sample H).

[0148] An especially good duration was obtained using a HA concentration of 0.65-0.8 wt. %. This was noticeable by an intense contrast that lasted until the very end of the surgery, which typically is 10 minutes. The staining intensity was good when using a TB concentration higher than 0.02 wt. %.

[0149] The staining compositions according to the invention provided an intense contrast even if no air bubble was injected. Being able to skip the use of the air bubble means less handling for the surgeon and hence less time consumption. The injection and subsequent removal of an air bubble typically adds 30 seconds to 1 minutes on a total duration of a cataract surgery of 10-15 minutes. Also, as with any surgical handling, there is always a risk that complications may arise.