Effect of incision size on early postoperative visual rehabilitation after cataract surgery and intraocular lens implantation

Comparative Study of Astigmatism through Superior and Lateral Small Incisions

PURPOSE

To prospectively compare the clinical results of two cataract surgery procedures through a 4.0-mm incision, differing only in the wound location (superior or lateral).

METHODS

168 eyes with cataract were randomly assigned to either procedure. Except for incision location, surgical methods were identical. Uncorrected visual acuity, keratometry and postoperative astigmatism were analyzed up to six months for after surgery.

RESULTS

Both groups had similar uncorrected visual acuity. Eyes in the superior incision group had significantly larger "against-the-rule" changes than those in the lateral incision group, and differences were significant at all measurement points from one week through six months after surgery. Patients with preoperative "with-the rule" astigmatism had smaller postoperative astigmatism after a superior incision and those with preoperative "against-the rule" astigmatism had less postoperative cylinder after a lateral incision. Differences between these groups were significant.

CONCLUSIONS

Both procedures gave satisfactory clinical results. Postoperative astigmatism could depend on the preoperative astigmatism and the wound location.

Surgically Induced Astigmatism after Manual Extracapsular Cataract Extraction or after Phacoemulsification Procedure

Astigmatic changes in three series of cataract surgical procedures were compared. The first two series comprised eyes having a manual extracapsular cataract extraction (ECCE) through a 12.0 mm or 8.0 mm incision and implant of a PMMA posterior chamber lens. The third series comprised eyes having phacoemulsification through a scleral pocket and implant of a PMMA posterior chamber lens. Preoperative keratometry measurements and corneal topography maps were compared with those obtained two days, one week, one, three and six months postoperatively. The keratometry measurements, obtained with computerized videokeratography, revealed: on day 2, 4.89 D (1st series), 3.95 D (2nd series), 2.66 D (3rd series); one week, respectively 4.46 D, 3.51 D and 2.14 D; one month, 0.65 D, 0.53 D and 0.05; three months, 1.44 D, 0.35 D and 0.36 D; six months, 1.36 D, 0.42 D and 0.48 D. The surgically-induced cylinder at three months was four times greater in the manual ECCE 12.0 mm incision series than in the phacoemulsification series. However, by six months all differences were markedly reduced. The results add to the growing evidence that the phacoemulsification procedure produces less astigmatism and more rapid visual rehabilitation than the manual ECCE procedure. Topographic analysis showed much less corneal steepening after phacoemulsification than after manual ECCE. However, all three surgical procedures offered satisfactory clinical results.

Assessment of cataract surgical outcomes in settings where follow-up is poor: PRECOG, a multicentre observational study

BACKGROUND

Poor follow-up after cataract surgery in developing countries makes assessment of operative quality uncertain. We aimed to assess two strategies to measure visual outcome: recording the visual acuity of all patients 3 or fewer days postoperatively (early postoperative assessment), and recording that of only those patients who returned for the final follow-up examination after 40 or more days without additional prompting.

METHODS

Each of 40 centres in ten countries in Asia, Africa, and Latin America recruited 40-120 consecutive surgical cataract patients. Operative-eye best-corrected visual acuity and uncorrected visual acuity were recorded before surgery, 3 or fewer days postoperatively, and 40 or more days postoperatively. Clinics logged whether each patient had returned for the final follow-up examination without additional prompting, had to be actively encouraged to return, or had to be examined at home. Visual outcome for each centre was defined as the proportion of patients with uncorrected visual acuity of 6/18 or better minus the proportion with uncorrected visual acuity of 6/60 or worse, and was calculated for each participating hospital with results from the early assessment of all patients and the late assessment of only those returning unprompted, with results from the final follow-up assessment for all patients used as the standard.

FINDINGS

Of 3708 participants, 3441 (93%) had final follow-up vision data recorded 40 or more days after surgery, 1831 of whom (51% of the 3581 total participants for whom mode of follow-up was recorded) had returned to the clinic without additional prompting. Visual outcome by hospital from early postoperative and final follow-up assessment for all patients were highly correlated (Spearman's rs=0·74, p<0·0001). Visual outcome from final follow-up assessment for all patients and for only those who returned without additional prompting were also highly correlated (rs=0·86, p<0·0001), even for the 17 hospitals with unprompted return rates of less than 50% (rs=0·71, p=0·002). When we divided hospitals into top 25%, middle 50%, and bottom 25% by visual outcome, classification based on final follow-up assessment for all patients was the same as that based on early postoperative assessment for 27 (68%) of 40 centres, and the same as that based on data from patients who returned without additional prompting in 31 (84%) of 37 centres. Use of glasses to optimise vision at the time of the early and late examinations did not further improve the correlations.

INTERPRETATION

Early vision assessment for all patients and follow-up assessment only for patients who return to the clinic without prompting are valid measures of operative quality in settings where follow-up is poor.

FUNDING

ORBIS International, Fred Hollows Foundation, Helen Keller International, International Association for the Prevention of Blindness Latin American Office, Aravind Eye Care System.

Osmotic cavitation of elastomeric intraocular lenses

In recent years, traditional rigid materials have been replaced with softer elastomers in intraocular lenses to minimize the size of the required surgical incision, thereby reducing patient recuperation time. However, water-filled cavities that may impact visual acuity are found in many of these new implants. We demonstrate that the cavitation observed in vivo can occur due to an osmotic pressure difference between the aqueous solution within the cavity and the external media in which the lens is immersed. By reducing the osmolarity of the external solution from 300 to 0mM, we observe an increase in cavity volume of almost a factor of 30. Further, we have developed a model for cavity growth assuming the controlling factor is diffusion of hydrophilic molecules from the polymer matrix into the cavity. We find that the experimental observations are consistent with the model and suggest that oligomeric species generated during polymerization are responsible for the observed cavitation.

Microincisional cataract surgery and Thinoptx rollable intraocular lens implantation

BACKGROUND

Microincisional cataract surgery is a safe procedure with a very short learning period for an experienced cataract surgeon and rollable ultrathin intraocular lenses eliminate the need for enlargement of corneal incision. The purpose of the study was to evaluate the safety and efficacy of cataract surgery through a corneal microincision and implantation of rollable ultrathin intraocular lenses. The setting was Dokuz Eylul University Medical Faculty, Ophthalmology Department, Izmir, Turkey and SSK Okmeydani Hospital, Ophthalmology Clinic, Istanbul, Turkey.

PATIENTS AND METHODS

Ninety eyes in 85 patients were operated on through clear corneal microincisions with sleeveless phacoemulsification and rollable intraocular lenses were implanted. Forty-six of the patients were men and 39 were women between the ages of 27 and 83, with a mean of 51 years. Two eyes had atrophic senile macular degeneration, 4 eyes had nonspecific retinal pigment epithelial changes with chorioretinal atrophy, and 4 patients had diabetes mellitus without retinopathy. Three eyes had posterior capsular opacifications of unknown etiology. Two eyes had primary open angle glaucoma (PAAG) with cup to disc ratios of about 0.5. Three eyes had dense nuclear sclerosis of grade 4 with very low visibility of retinal structures. Other patients had no ocular or systemic pathology other than nuclear/corticonuclear cataract of grade 2-3. Uncorrected and best spectacle-corrected distance and near visual acuities, keratometric values, and refractive status were noted preoperatively and 1 week, 1 month, and 6 months postoperatively. Statistical analysis of keratometric changes between preoperative and postoperative findings was performed using the paired samples t test.

RESULTS

At 6 months postoperatively, 1 patient had a best spectacle-corrected visual acuity (BSCVA) of 0.2, the patient with atrophic senile macular degeneration. The rest of the eyes achieved a BSCVA of 0.63 or better. At 6 months postoperatively, 55 (61.11%) eyes had uncorrected visual acuities (UCVA) equal to or better than 0.8 and 83 (92.22%) eyes had BSCVA equal to or better than 0.8 according to the Snellen chart. The mean postoperative corneal astigmatisms at 1 week, 1 month, and 6 months were 0.69+/-0.43 D, 0.66+/-0.46 D and 0.65+/-0.48 D respectively. Statistical analysis revealed a significant change in corneal astigmatisms at the 1st week visit (p<0.05), but not at the 1st and 6th month visits (p>0.05) compared with preoperative findings.

CONCLUSION

Based on the limited data in the literature and in this study, it is not possible to make concrete decisions about the benefits and disadvantages of the ThinOptx IOL for longer durations. Intraoperatively, this IOL apparently eliminates the need for enlargement of the corneal incision during implantation. However, the statistical insignificance of induced astigmatisms after microincisions and classical phacoincisions should also be taken into consideration. We conclude that ThinOptx IOL is a pioneering intraocular lens implant that will contribute to the exciting future of cataract refractive surgical procedures. However, both clinical and laboratory investigations are needed to clearly describe the long-term effectiveness of this new rollable IOL.

[Teaching phacosection in a tropical setting]

PURPOSE

The aim of this study was to prospectively evaluate the training of a Malagasy ophthalmologist, already proficient in classic manual extracapsular cataract extraction (ECCE), in a small incision manual technique (phacosection).

MATERIALS AND METHODS

Within the activity of the Sight First program to fight blindness in Madagascar, the ophthalmologist of Majunga recruited patients presenting total white cataracts. These patients were operated by phacosection using the local hospital's usual instrumentation along with two specific phacosection instruments and extra single-use material (a precalibrated 3.2 mm knife and viscoelastic products). Peribulbar anesthesia with eye pressure was provided. Postoperative follow-up (visual acuity and corneal status) was conducted on days 1, 7 and 30.

RESULTS

Forty-four eyes were operated, the first seven by the instructor assisted by the local ophthalmologist, the next 36 by the local ophthalmologist assisted by the instructor. Five postoperative complications were noted: two cases of posterior capsular rupture (one during implantation) and three cases needing reoperation with aspiration of residual cortical masses. Induced astigmatism was low and visual rehabilitation was good, with all corneas clear at day 30.

DISCUSSION

The results are quite acceptable given the training period, with only two marked complications (one not related to the operative technique) and good visual rehabilitation in less than 2 weeks. This small incision technique allowed reduction of induced astigmatism and risk-free management of total white cataracts (independent of operator).

CONCLUSION

Small incision manual ECCE by phacosection is a safe, possible management option for difficult cataracts in a tropical setting with only a small increase in cost. Moreover, the training of an ophthalmologist mastering classic manual ECCE appears rapid and risk-free for patients.

Extracapsular cataract surgery compared with manual small incision cataract surgery in community eye care setting in western India: a randomised controlled trial

AIM

To study "manual small incision cataract surgery (MSICS)" for the rehabilitation of cataract visually impaired and blind patients in community based, high volume, eye hospital setting; to compare the safety and effectiveness of MSICS with conventional extracapsular cataract surgery (ECCE).

METHODS

In a single masked randomised controlled clinical trial, 741 patients, aged 40-90 years, with operable cataract were randomly assigned to receive either MSICS or ECCE and operated upon by one of eight participating surgeons. Intraoperative and postoperative complications were graded and scored according to the Oxford Cataract Treatment and Evaluation Team recommendations. The patients were followed up at 1 week, 6 weeks, and 1 year after surgery and their visual acuity recorded.

RESULTS

This paper reports outcomes at 1 and 6 weeks. 706 of the 741(95.3%) patients completed the 6 week follow up. 135 of 362 (37.3%) of ECCE group and 165 of 344 (47.9%) of MSICS group had uncorrected visual acuity of 6/18 or better after 6 weeks of follow up. 314 of 362 (86.7%) of ECCE group and 309 of 344 (89.8%) of MSICS group had corrected postoperative vision of 6/18 or better. Four of 362 (1.1%) of ECCE group and six of 344 (1.7%) of MSICS group had corrected postoperative visual acuity less than 6/60. There were no significant differences between the two groups for intraoperative and severe postoperative complications.

CONCLUSION

MSICS and ECCE are both safe and effective techniques for treatment of cataract patients in community eye care settings. MSICS needs similar equipment to ECCE, but gives better uncorrected vision.

Effects on visual function of glistenings and folding marks in AcrySof intraocular lenses

PURPOSE

To study the effects on visual function of glistenings and folding marks in AcrySof (Alcon) intraocular lenses (IOLs).

SETTING

Department of Ophthalmology, Dokuz Eylül University, School of Medicine, Izmir, Turkey.

METHODS

This study included 91 eyes that had phacoemulsification and in-the-bag AcrySof IOL implantation. Slitlamp, visual acuity, and contrast sensitivity evaluations were used to assess all cases. Observations of folding marks and glistenings in the IOL optic were noted. The glistenings were graded from 0 to +4. Eyes with coexisting pathology that could affect visual acuity (n = 15) were excluded from the study. After the exclusion, the visual acuity and contrast sensitivity in 28 eyes with glistenings were compared with those in 48 eyes without glistenings.

RESULTS

Localized folding marks away from the central visual axis of the IOL were identified in 25 eyes (27.4%). Glistenings were observed in 34 eyes (37.1%), 6 of which were excluded for coexisting pathology. There was no statistically significant difference in visual acuity and contrast sensitivity at low or medium spatial frequencies between eyes with glistenings and those without (P >.05); however, a statistically significant difference was noted at the high spatial frequency (P <.01). There was no difference in visual acuity or contrast sensitivity between eyes with folding marks and those without (P >.05).

CONCLUSION

Although glistenings and folding marks were observed after the implantation of AcrySof IOLs, they did not significantly affect visual function.

Extracapsular cataract extraction compared with small incision surgery by phacoemulsification: a randomised trial

BACKGROUND

Cataract extraction constitutes the largest surgical workload in ophthalmic units throughout the world. Extracapsular cataract extraction (ECCE), through a large incision, with insertion of an intraocular lens has been the most widely used method from 1982 until recently. Technological advances have led to the increasing use of phacoemulsification (Phako) to emulsify and remove the lens The technique requires a smaller incision, but requires substantial capital investment in theatre equipment. In this randomised trial we assessed the clinical outcomes and carried out an economic evaluation of the two procedures.

METHODS

In this two centre randomised trial, 232 patients with age related cataract received ECCE, and 244 received small incision surgery by Phako. The main comparative outcomes were visual acuity, refraction, and complication rates. Resource use was monitored in the two trial centres and in an independent comparator centre. Costs calculated included average cost per procedure, at each stage of follow up.

RESULTS

Phako was found to be clinically superior. Surgical complications and capsule opacity within 1 year after surgery were significantly less frequent, and a higher proportion achieved an unaided visual acuity of 6/9 or better (<0.2 logMAR) in the Phako group. Postoperative astigmatism was more stable in Phako. The average cost of a cataract operation and postoperative care within the trial was similar for the two procedures. With the input of additional spectacles for corrected vision at 6 months after surgery, the average cost per procedure was pound359.89 for Phako and pound367.57 for ECCE.

CONCLUSION

Phako is clinically superior to ECCE and is cost effective.

Fourier analysis of irregular astigmatism after implantation of 3 types of intraocular lenses

PURPOSE

To evaluate irregular astigmatism after silicone, acrylic, and poly(methyl methacrylate) (PMMA) intraocular lens (IOL) implantation using Fourier analysis of videokeratography data.

METHODS

Two hundred forty eyes having phacoemulsification and IOL implantation were randomly assigned to 1 of 3 groups: 3.5 mm incision and silicone IOL, 4.1 mm incision and acrylic IOL, or 6.5 mm incision and PMMA IOL. All eyes had videokeratographic examinations preoperatively and 2, 4, and 10 days and 1 and 3 months postoperatively. The dioptric data of the central cornea were decomposed into spherical equivalent, regular astigmatism, and irregular astigmatism (decentration and higher-order irregularity) components using Fourier analysis.

RESULTS

Regular astigmatism in the PMMA group was greater than in the silicone and acrylic groups. Decentration in all 3 groups increased significantly postoperatively but virtually returned to preoperative levels by 10 days. No significant difference was observed among the 3 groups. Higher-order irregularity significantly increased after surgery in all 3 groups. The higher-order irregularity in the PMMA group persisted for up to 1 month, while that in the silicone and acrylic groups returned to preoperative levels by 4 days, resulting in significant differences between these groups 10 days and 1 month after IOL implantation.

CONCLUSION

Irregular astigmatism, both the decentration and higher-order irregularity components, increased significantly after 3 types of scleral tunnel incisions for silicone, acrylic, or PMMA IOL implantation but returned to preoperative levels soon after surgery except for the higher order irregularity after PMMA IOL implantation.

Phacoemulsification and modern cataract surgery

The techniques and results of cataract surgery have changed dramatically during the past three decades. In the USA, we have moved from intracapsular cataract extraction as the preferred technique to almost exclusively extracapsular techniques. Smaller incisions have become the standard, with phacoemulsification now being the method of choice for most surgeons. Along with these advances have come improved intraocular lens materials and designs, especially well suited for use with smaller incisions. Phacoemulsification as a method to remove the cataractous lens was first proposed more than 20 years ago. Advances in techniques and equipment have led to a dramatic increase in the popularity of phacoemulsification with increased safety and efficiency. Viscoelastic agents have been developed synchronously with modern phacoemulsification techniques, playing an integral role in the success of this new technology. Improved surgical techniques for removing the anterior lens capsule have decreased the incidence of both intraoperative and postoperative capsular complications. Nucleus removal, formerly performed primarily in the anterior chamber, is now performed in the posterior chamber, decreasing damage to the corneal endothelium. Improved wound construction allows many wounds to be left unsutured, and smaller wounds allow shorter recovery time and greater intraoperative control and safety. Intraocular lenses can have smaller optic sizes and still maintain accurate centration. Foldable intraocular lenses can take advantage of the smaller incision, even further shortening the time to visual recovery. Continual evolution of this technology promises to further improve patient outcomes after cataract surgery.

Discharging routine phacoemulsification patients at one week

The reduction of surgically induced astigmatism and rapid refractive stabilisation after phacoemulsification have been well studied and often lead to reduced follow-up. In this prospective study we reviewed a cohort of 100 patients discharged with a refractive prescription at their 1 week post-operative appointment following routine sutureless phacoemulsification through a corneal or scleral section. The aim was to assess the incidence of late pathology and need for review. Eighty-eight patients attended for review between 3 and 4 months post-operatively, of whom 8 (9.1%) who had been symptomatic had already visited ophthalmic casualty. Nine (10.2%) benefited from the follow-up appointment: 4 were given a new refractive prescription that increased their Snellen visual acuity by 1 line; the other 5 were all symptomatic or had incidental findings. We feel that provided there is easy access to the eye department, early discharge with or without refraction is justifiable as those with surgically related pathology at any stage are symptomatic.

Three year prospective, randomized evaluation of intraocular lens implantation through 3.2 and 5.5 mm incisions

PURPOSE

To compare the long-term clinical results of two small incision cataract surgery procedures.

SETTING

Seven centers in Japan.

METHODS

Two hundred eyes were randomly assigned to receive a silicone intraocular lens (IOL) through a 3.2 mm incision or a poly(methyl methacrylate) (PMMA) IOL through a 5.5 mm incision. Except for incision size and implantation technique, the surgical methods were identical. Uncorrected and corrected visual acuity, keratometry, flare-cell intensity, specular microscopy, and neodymium:YAG (Nd:YAG) laser posterior capsulotomy rate were analyzed up to 3 years after surgery.

RESULTS

Eyes in the 3.2 mm incision group had significantly better uncorrected and corrected visual acuity in the early postoperative period and lower aqueous flare intensity immediately after surgery, but these differences disappeared after the first postoperative month. However, surgically induced astigmatism was significantly less in the 3.2 mm incision group than in the 5.5 incision group throughout the study. The Nd:YAG laser capsulotomy rate was higher in the silicone IOL group (23.5% at 3 years postoperatively) than in the PMMA IOL group (18.4%) but the difference was not statistically significant.

CONCLUSION

Smaller incision cataract surgery led to early recovery of visual function in the short term and less induced astigmatism in the long term.

In vitro analysis of AcrySof intraocular lens glistenings in AcryPak and Wagon Wheel packaging

PURPOSE

To compare the formation of "glistenings" in acrylic intraocular lenses (IOLs) packaged in Wagon Wheel and AcryPak packaging systems.

SETTING

John Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

METHODS

Acrylic IOLs in Wagon Wheel (WW) and AcryPak (AP) packaging were analyzed in vitro. The lenses were placed in a test chamber with a controlled temperature and evaluated every 48 hours for 336 hours. The presence of glistenings within the lens optic was assessed using slitlamp evaluation and a quantitative microscopic evaluation with an image analysis system.

RESULTS

When maintained at a constant temperature, the WW-packaged IOLs showed no glistening formation and the AP-packaged IOLs, significant glistening formation. Glistenings were noted in the WW-packaged IOLs only under fluctuating temperature conditions. Quantitative image analysis confirmed the presence of glistenings only in AP-packaged IOLs maintained at a constant temperature.

CONCLUSION

The glistenings in AcrySof IOLs were temperature dependent and confined to IOLs packaged in AcryPak folders and maintained at constant (body) temperatures. These findings are believed to be consistent with fluid formation within the acrylic optic, somehow related to the AcryPak packaging system.

Induced astigmatism after 4 and 6 mm scleral tunnel incision. A randomized study

PURPOSE

To study the surgically induced astigmatism after phacoemulsification through either a 4 or a 6 mm scleral tunnel incision by using multiple analyses of astigmatism.

METHODS

197 eyes from 186 patients scheduled for phacoemulsification between October 1992 and March 1994 were randomly assigned two different-sized incisions with follow-ups at 1 day, 1 week, 2 weeks, 1 month and 4 months after surgery. The surgically induced astigmatism was evaluated using at each follow-up: 1) The subtraction method, 2) vector analysis, 3) vector decomposition, 4) Cravy's vertical vector, 5) Naeser's polar values, and 6) the algebraic method.

RESULTS

By subtraction, without regard to axis, the induced astigmatism 4 months after surgery was +0.04 D and +0.18 D in the 4 mm and the 6 mm incision group, respectively. By vector analysis, the numerical value of the induced cylinder was stable one month after surgery at 0.61 D and 0.77 D in the 4 mm and in the 6 mm group, respectively. However, cylinder orientation was not found stable until 4 months after surgery, where 94% and 96% of the surgically induced astigmatism (vector decomposition) was against-the-wound in the two groups, respectively. By Cravy's method, the mean induced astigmatism changed from -0.08 D to -0.32 D and from -0.42 D to -0.60 D between 1 and 4 months in the 4 mm and the 6 mm group, respectively. Similar values were found with Naeser's method and with the algebraic method.

CONCLUSION

We conclude the mean cylinder of the surgically induced astigmatism (vector analysis) to be stable 1 month after phacoemulsification with both the 4 mm and 6 mm scleral tunnel incision. However, the direction of the induced axis (vector decomposition) was still drifting between 1 and 4 months in both groups. These astigmatic changes were adequately described using vector analysis and vector decomposition.

Intraocular lens materials and styles: a review

Biomaterial science has lead to the development of a variety of foldable intraocular lens (IOL) biomaterials. This literature review examines these lenses from both a basic science and a clinical perspective. By most parameters, hydrogel, soft acrylic and silicone IOL are better than polymethylmethacrylate (PMMA) lenses. Plate haptic silicone IOL have the lowest incidence of cystoid macula oedema and posterior capsule opacification, but these lenses require an intact anterior capsularhexis and posterior capsule. Yttrium aluminium garnet (YAG) laser capsulotomy must be delayed at least 3 months to avoid posterior lens dislocation. Silicone has the lowest threshold for YAG laser damage of all IOL materials and also adheres irreversibly to silicone oil with subsequent optical impairment. Three piece silicone IOL with polypropylene haptics have a higher incidence of decentration, pigment adherence and capsule opacification compared with PMMA haptics. Hydrogel lenses are very biocompatible and resistant to YAG laser damage, but pigment adheres to the surface more readily than PMMA. Soft acrylic IOL unfold slowly, resulting in controlled insertion, but it is possible to crack the lens and some lenses develop glistenings due to water accumulation. There are significant socioeconomic implications to the large differences in posterior capsule opacification rates between the various biomaterials and the lens styles.

Cataract patients in a defined Swedish population 1986-1990. VIII. Postoperative astigmatism, intraocular pressure and visual acuity

PURPOSE

Cataract surgery is often followed by a certain amount of astigmatism that changes in the postoperative period. However, there are large variations in both size and changes of the postoperative astigmatism. I have analysed the variations and the influence of different explanatory variables on the postoperative astigmatism.

METHODS

Data for all patients undergoing cataract surgery from 1986 up to and including 1990 in the Lund Health Care District were prospectively recorded. Except for cases operated on with both keratoplasty and cataract, all cases were included in the study. The different explanatory variables considered included sex, age, preoperative axial length, preoperative average keratometry, preoperative intraocular pressure, glaucoma history, diabetes history, uveitis history (including both anterior and posterior uveitis), and a history of rheumatoid arthritis.

RESULTS

Besides age and sex, several variables significantly influenced the development of size and/or change in the postoperative astigmatism. They were preoperative astigmatism (polar value), preoperative intraocular pressure, and whether or not the cataract patient had an insulin dependent diabetes. Phacoemulsification as extraction mode, the location of the incision, complications at surgery, and whether or not a sphincterotomy was performed also influenced the two parameters of astigmatism. It was also important whether or not the operation was performed by a high volume surgeon.

CONCLUSION

In this material, the most important predisposing factors for rapid changes in the postoperative astigmatism were large preoperative astigmatism (polar value), young age, low preoperative intraocular pressure, if an ECCE were chosen as the extraction type, and the surgeon. The same variables and, in addition, if the location of the incision was anterior to the limbus were the most important explanatory variables in generating an early, large with-the-rule astigmatism.

Corneal changes after cataract surgery with 5.0 mm sutured and 3.5 mm sutureless clear corneal incisions

PURPOSE

To study corneal changes after endocapsular phacoemulsification cataract extraction and intraocular lens (IOL) implantation with a 3.5 mm clear corneal sutureless incision or a 5.0 mm clear corneal incision with an absorbable suture.

SETTING

Northwest Kansas Eye Clinic, Hays, Kansas, USA.

METHODS

In a prospective study, 200 eyes were randomly distributed into two groups. Group A comprised 100 eyes that had a silicone IOL inserted through a 3.5 mm sutureless clear corneal incision. Group B comprised 100 eyes that had a 5.0 mm poly(methyl methacrylate) (PMMA) IOL inserted through a 5.0 mm clear corneal incision; one half of the closures used a single radial suture (Group B1), and the other half, an X suture (Group B2). Preoperatively, corneal topography and corneal endothelial cell counts were performed. Six to 8 months postoperatively, they were repeated and evaluated. Differential topography was used to determine the difference between the preoperative and postoperative corneas. During the final postoperative visit, IOL centration was evaluated.

RESULTS

All closures produced only minimal changes in the corneal topographic indices. The postoperative corneas closely resembled the preoperative corneas. Polar K values showed a slight astigmatic shift in all groups. Group B2 was the only one to exhibit a with-the-rule shift. The change in endothelial cell counts was minimal and comparable in all three groups.

CONCLUSION

The small amount of change in the corneal indices, especially in surface regularity, indicates that all corneas were relatively comparable and stable 6 to 9 months postoperatively regardless of the type of incision and closure method.

Intraocular lens implantation through 3.2 versus 4.0 mm incisions

PURPOSE

To prospectively compare the clinical results of two small incision cataract surgery procedures: silicone intraocular lens (IOL) implantation through a 3.2 mm incision and poly(methyl methacrylate) IOL implantation through a 4.0 mm cruciate incision.

SETTING

Department of Ophthalmology, Ramón y Cajal Hospital, Madrid, Spain.

METHODS

One hundred twenty eyes with cataract were randomly assigned to either procedure. Except for incision width, identical surgical methods were used in every case. Data on uncorrected visual acuity, keratometry, and postoperative astigmatism were analyzed up to 6 months after surgery.

RESULTS

Both groups had similar uncorrected visual acuities. Mean postoperative corneal astigmatism was against the rule with both techniques, and it remained stable during the study. No significant differences between groups were found (P > .1).

CONCLUSION

Both procedures offered satisfactory clinical results and were associated with postoperative against-the-rule astigmatism despite the use of the nylon suture.

Cracked cartridges during foldable intraocular lens implantation

We describe five routine phacoemulsification procedures in which a longitudinal split in the injector cartridge occurred during foldable intraocular lens (IOL) implantation. In some cases, this was associated with a broken lens. All lenses (STAAR AA-4203VF) were folded, and implantation was attempted through a 3.5 mm corneal or scleral incision. Visual outcome was not adversely affected in any case. The systems for introducing foldable IOLs have not been perfected, and further refinements in materials and techniques are required.

Effect of foldable intraocular lens insertion on incision width

PURPOSE

To determine whether the surgical incision enlarges during insertion of foldable intraocular lenses (IOLs).

SETTING

Mackool Eye Institute, Astoria, New York.

METHODS

A variety of IOL insertion devices and foldable and injectable IOLs were inserted through 3.0 or 3.5 mm keratome incisions made in cadaver eyes. The external and internal incision widths were then measured.

RESULTS

Each 3.0 mm incision was enlarged externally by 0.10 to 0.65 mm and internally by 0.50 to 0.75 mm by a variety of insertional devices and IOLs. One forceps-IOL combination required a 3.5 mm incision for lens insertion and resulted in a 0.4 mm enlargement of the internal incision.

CONCLUSIONS

The use of a 3.5 mm incision and insertion devices that do not enlarge an incision of this size might be desirable.

Evaluation of the first 50 ACR360 acrylic intraocular lens implantations

PURPOSE

To evaluate the clinical results of implantation of the ACR360 soft acrylic intraocular lens (IOL).

SETTING

Civico Hospital, Lugano, Switzerland.

METHODS

This prospective, medium-term study comprised the first 50 consecutive patients who had small incision scleral tunnel phacoemulsification and implantation of an ACR360 acrylic IOL (loptex/Allergan). Intraoperative and postoperative complications, best corrected visual acuity (BCVA), intraocular pressure (IOP), preoperative and postoperative astigmatism, and IOL centration were recorded. Mean follow-up was 12 months +/- 3 (SD).

RESULTS

One day postoperatively, 94% of best cases (n = 46) achieved a BCVA of 20/40 or better and 54%, 20/25 or better. At 2 weeks, 98% had 20/40 or better and 78%, 20/25 or better. After 6 months, all patients achieved a BCVA of 20/40 or better and 83%, 20/25 or better. No statistically significant changes in keratometric astigmatism or IOP occurred.

CONCLUSIONS

The ACR360 IOL gave clinical results comparable to those of other foldable lenses; however, it can also be implanted in cases of intraoperative capsular complications and in eyes with intravitreal silicone oil. Development of an injecting system for implantation and substituting the polypropylene loops with poly(methyl methacrylate) haptics could improve lens quality.

Corneal astigmatism after phacoemulsification and lens implantation through unsutured scleral and corneal tunnel incisions

PURPOSE

We compared the changes in corneal astigmatism after phacoemulsification and intraocular lens implantation in 93 consecutive eyes with unsutured 4-mm superior scleral tunnel incisions to those through 105 consecutive eyes with unsutured 3.2- to 3.5-mm temporal corneal tunnel incisions.

METHODS

Keratometry measurements were obtained preoperatively and at postoperative day 1, week 1, and week 6. Group differences in scalar and vector astigmatism were compared by using analysis of variance methods.

RESULTS

Mean scalar astigmatism in the scleral incision group changed from preoperative astigmatism by 0.65 diopter at postoperative day 1, 0.37 diopter at postoperative week 1, and 0.13 diopter at postoperative week 6. Mean scalar astigmatism in the corneal incision group changed from preoperative astigmatism by 0.39 diopter at postoperative astigmatism by 0.39 diopter at postoperative day 1, 0.21 diopter at postoperative week 1, and 0.13 diopter at postoperative week 6. Mean vector astigmatism in the scleral incision group changed 1.26 diopters at 80 degrees at postoperative day 1, 1.05 diopters at 83 degrees at postoperative week 1, and 0.42 diopter at 103 degrees at postoperative week 6. Mean vector astigmatism in the corneal incision group changed 0.77 diopter at 90 degrees at postoperative week 1, and 0.61 diopter at 89 degrees at postoperative week 6. The differences were statistically significant (P = .003) only by vector analysis at the postoperative day 1 examination.

CONCLUSIONS

We found significantly greater with-the-rule change in astigmatism in the scleral incision group than in the corneal incision group on the first postoperative day. The effect disappeared by the sixth postoperative week.

Two year clinical study of a soft acrylic intraocular lens

PURPOSE

To assess the efficacy and safety of a soft acrylic intraocular lens (IOL) in small incision cataract surgery.

METHODS

Sixty-four eyes of 64 patients (mean age 71.0 +/- 7.7 [SD] years) who had phacoemulsification and implantation of a soft acrylic IOL were followed for 2 years.

RESULTS

At day 1, 96.9% of patients had corrected visual acuity of 20/40 or better, and 50.0% had 20/20 or better. At 2 years postoperatively, 100% had 20/40 or better, and 86.3% had 20/20. Surgically induced keratometric cylinder remained quite stable throughout the 2 year follow-up period, with axis-based astigmatism of +/- 0.3 diopters. Flare intensity measured with the laser flare-cell meter was less than that with other type of IOLs measured, including poly(methyl methacrylate) and silicone. Neodymium:YAG laser capsulotomy was performed in seven cases (11.1%). without causing damage to the optic. No other postoperative complications were encountered.

CONCLUSION

Soft acrylic IOLs have clinically apparent advantages in small incision cataract surgery.

Scanning electron microscopic analysis of foldable acrylic and hydrogel intraocular lenses

OBJECTIVE

To analyze the surface quality of foldable acrylic and hydrogel intraocular lenses (IOLs).

SETTING

Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, and Institute of Anatomy and Cellular Biology, University of Giessen, Germany.

METHODS

We studied eight foldable IOL models with optics made of six different acrylate/methacrylate polymers: Acrylens ACR360 (loptex), AcrySof MA60BM (Alcon), MemoryLens U940A (Mentor), 92S and 92C (Morcher), Hydroview H60M (Storz), HydroSof SH30BC (Alcon), and ISH66 (Corneal). Four IOLs of each design were examined. Light and scanning electron microscopy were performed before and after IOL folding with forceps.

RESULTS

All IOL models had excellent optic and haptic surfaces. The haptic-optic junctions revealed minimal empty spaces or irregularities in three of the five three-piece IOLs and smooth surfaces in all one-piece IOLs. Minimal surface alterations and superficial defects caused by folding were detectable in the two acrylate (acrylic) IOLs (loptex ACR360, Alcon MA60BM) with low water content.

CONCLUSION

Intraocular lenses of acrylate/methacrylate polymers had excellent surface quality. The acrylic IOLs were vulnerable to mild folding or forceps defects; however, these were less marked than those previously noted with poly(methyl methacrylate) IOLs.

Long-term clinical results of AMO PhacoFlex model SI-18 intraocular lens implantation

The AMO PhacoFlex Model SI-18 was the first commercially available three-piece silicone intraocular lens (IOL) for use in small incision cataract surgery. Allergan Medical Optics' silicone IOLs have been implanted in more than 750,000 patients worldwide over the past eight years. This report of the FDA clinical investigation of the AMO PhacoFlex model SI-18 IOL summarizes one year follow-up data from the initial premarket approval clinical trial on 500 core patients implanted with the SI-18 lens. One-year follow-up data from 5,860 patients in the modified core group and three-year follow-up data on the 500 patient core/modified core group are also presented. At three years postoperatively, 91.3% of best case core/modified core patients achieved 20/40 or better corrected visual acuity. Overall incidence of persistent complications at three years was 3.2%.

The correlation between incision size and corneal shape changes in sutureless cataract surgery

PURPOSE

To examine the correlation between incision size and corneal shape changes in sutureless surgery using corneal topography.

METHODS

Two hundred eyes undergoing sutureless cataract surgery were assigned randomly to three groups according to the incision size: group A, 3.2-mm incision; group B, 4.0-mm incision; and group C, 5.0-mm incision. All eyes were examined by corneal topography preoperatively as well as at 1 week and at 1, 3, and 6 months after surgery.

RESULTS

In the average of difference maps of eyes in the 3.2-mm incision group, a wound-related flattening in the peripheral cornea occurred 1 week after surgery, but decreased rapidly thereafter. Subsequently, no significant changes were observed in the cornea after 1 month. In the 4.0-mm incision group, with a reduction of the wound-related peripheral flattening, an irregular steepening appeared in the lower central cornea 6 months after surgery. In the 5.0-mm incision group, a similar steepening in the lower cornea occurred just after surgery. This steepening persisted and even extended to the upper central cornea in its later postoperative periods.

CONCLUSION

The 3.2-mm incision hardly produced any irreversible corneal shape changes, whereas both the 4.0- and 5.0-mm incisions caused a persistent irregular steepening in the central cornea.

Astigmatic changes after cataract surgery with 5.1 mm and 3.5 mm sutureless incisions

We evaluated postoperative keratometric astigmatism in 80 eyes that had phacoemulsification and intraocular lens implantation through sutureless corneal incisions. The eyes were separated into two groups based on the use of rigid ovoid or foldable silicone lenses inserted through 5.1 mm corneal lip incisions or 3.5 mm lip incisions, respectively. In the early postoperative period (one to three months), vector analysis showed less induced astigmatism in the 3.5 mm group than in the 5.1 mm group. Uncorrected visual acuity during the postoperative period was also better in the smaller incision group.

Comparative study of intraocular lens implantation through 3.2- and 5.5-mm incisions

PURPOSE

To prospectively and comprehensively compare the clinical results of two small-incision cataract surgery procedures, silicone intraocular lens (refractive index of 1.46) implantation through a 3.2-mm incision and polymethylmethacrylate intraocular lens implantation through a 5.5-mm incision.

METHODS

Two hundred eyes with cataract randomly were assigned to either procedure. Except for incision size, identical surgical methods were used in every case. Data on uncorrected and corrected visual acuity, keratometry, corneal topography, flare-cell measurement, fluorophotometry, specular microscopy, glare disability measurement, and photographic examination of intraocular lens decentration were analyzed up to 6 months after surgery.

RESULTS

Eyes in the 3.2-mm incision group displayed significantly better uncorrected and corrected visual acuity in the early postoperative period, lower aqueous flare intensity and cell counts immediately after surgery, less operatively induced astigmatism throughout the study period, and less corneal topographic changes taken 3 months after surgery. No significant between-group differences were noted for other parameters. Complications in the two groups were few and comparable.

CONCLUSION

Both procedures of small-incision cataract surgery offered satisfactory clinical results, but 3.2-mm incision cataract surgery allowed significantly earlier recovery of visual function and better preservation of corneal shape.

Small incision surgery with the STAAR Elastimide three-piece posterior chamber intraocular lens

One hundred twelve patients scheduled for uncomplicated cataract removal were randomly assigned to receive a STAAR Elastimide three-piece foldable intraocular lens inserted through a 4.0 mm incision or a STAAR poly(methyl methacrylate) (PMMA) lens inserted through a 7.0 mm incision. The same surgeon performed all surgeries using identical techniques, except for incision size and number of sutures. Patients receiving Elastimide lenses had significantly better uncorrected visual acuity postoperatively than patients receiving PMMA lenses and also had significantly less keratometric cylinder, surgically induced cylinder (vector method), and refractive cylinder. The Elastimide foldable lens offers the advantages of small incision surgery for patients who require a three-piece lens.