Future Intraocular Lens Technologies

The future of intraocular lens (IOL) technology has already begun with a number of recent innovations. The postoperative change of refractive power will lead to a customized fine-tuning that provides patients with the individual vision they expect and with as much spectacle independence as possible. The latest-generation (2.0) Light-Adjustable Lens (RxSight) was recently introduced into clinical practice, with the first results being very encouraging. Other methods of altering the power of an already implanted IOL are under development. The same can be said about the correction of presbyopia, the so-called last frontier in refractive surgery. Extended depth-of-focus IOLs have been introduced, as has the technology of the pinhole IOL. The latter has therapeutic potential beyond the refractive aspect and has already proven helpful in cases of iris defects and irregular corneas. Several technologies are currently being tested to achieve-finally-an accommodative IOL. One such concept uses the (remaining) strength of the ciliary muscle, whereas another is triggered by the pupil reaction when shifting focus from far to near. Not an IOL itself, but rather a high-tech innovation that so far has mostly been implanted during cataract surgery, is a microelectronic sensor that measures habitual intraocular pressure (IOP) at any given time and promises to revolutionize the management of glaucoma patients. The last generation of this device (Eyemate; Implandata Opthalmics Products GmbH) is implanted during small-incision cataract surgery; the latest development is an even smaller sensor that will be inserted suprachoroidally before, in the near future, such a device will be part of a capsular ring. These IOP sensors are a prime example that IOL technology will continue to be a driving force in ophthalmology, with a positive impact far beyond cataract surgery.

Small incision intraocular lens: past, present and future

Research indicates that silicone is comparable to or exceeds PMMA as an intraocular lens material. Insertion of silicone lenses does, however, continue to be a source of discussion and studies continue to develop more affective insertion instrumentation. Hydrogel also appears to be a viable material for intraocular lenses. Because hydrogel can be dehydrated and inserted flat in the eye with forceps, there is no problem with insertion instrumentation. Studies with these lens materials is preliminary and ongoing. Future work will include work with acrylics, endocapsular surgery (liquid gels, injectable and inflatable lenses), a teledioptric lens for macular degeneration, and an intraocular biofocal. The future also holds further silicone and hydrogel studies and the possible development of other materials for intraocular lenses all in search of the optimum intraocular lens material and design.

[Aberrometry results of a new IOL model with variable refractive surface]

The article presents the aberrometry results of a new intraocular lens (IOL) model with variable refractive surface of own design. By changing the pressure of silicone oil inside the artificial lens three levels of refractive power were achieved: 17.5D; 20.0D; 22.0D. The quality of the experimental optical system is comparable to that of a human eye after in vivo implantation of a ReSTOR multifocal IOL. Accommodating IOLs with refractive power varying within 4.5D are capable of maintaining the quality of retinal image, thus, ensuring high visual acuity.

Toric intraocular lenses: historical overview, patient selection, IOL calculation, surgical techniques, clinical outcomes, and complications

We present an overview of currently available toric intraocular lenses (IOLs) and multifocal toric IOLs. Relevant patient selection criteria, IOL calculation issues, and surgical techniques for IOL implantation are discussed. Clinical outcomes including uncorrected visual acuity, residual refractive astigmatism, and spectacle independency, which have been reported for both toric IOLs and multifocal toric IOLs, are reviewed. The incidence of misalignment, the most important complication of toric IOLs, is determined. Finally, future developments in the field of toric IOLs are discussed.

Cataract and refractive surgery in ; a survey of KSCRS members from 1995~2006

PURPOSE

This purpose of this report was to study trends in cataract and refractive surgeries conducted during the past twelve years and to compare results to previous reports from the ASCRS and New Zealand (NZ) in order to forecast future medical services.

METHODS

We surveyed members of the Korean Society of Cataract and Refractive Surgery (KSCRS) every year from 1995 to 2006, and studied changes in cataract and refractive surgeries (RS).

RESULTS

The duration of hospitalization has been gradually decreasing to the point that a one day hospitalization following surgery has become common. The rate of topical anesthesia use has significantly increased since 1998. Sutureless incision methods are now commonly practiced. The use of acryl IOL as an optic material has been gradually increasing for cataract surgeries. KSCRS members showed an interest in the special intraocular lenses as multifocal IOL. While Excimer laser PRK was the most popular refractive surgery during the first stage, KSCRS members increasingly prefer LASIK to the Excimer laser PRK. Regression of the corrected visual acuity, dry eye, night halo, and flashes were the most common complications following refractive surgeries. Medical disputes related to PRK and LASIK have been gradually increasing throughout the study period.

CONCLUSIONS

We confirm that the KSCRS practice styles for cataract and RS are similar to those of the ASCRS and NZ. We infer a world-wide trend from the comparison of these three societies.

Advances in cataract surgery and intraocular lenses

Cataract surgery is one of the most common medical procedures among persons age 65 and older. Once an inpatient procedure, it has become a simple outpatient surgery with extremely low rates of morbidity. With the development of implantable intraocular lenses (IOLs), patients undergoing cataract surgery gained the benefit of corrected pre-existing refractive error, astigmatism, and presbyopia. This article reviews developments in cataract surgery and describes current IOL technology.

[Childhood blindness. VISION 2020 and experiences in an African city]

The struggle against childhood blindness is being given high priority by the WHO. In regions of the world countries where the income per head is low there are 5 times as many blind children as in wealthy countries (1.5/1000 vs 0.3/1000 children). In developing countries cataract is regarded as the main cause of blindness in both childhood and adulthood. If all cataracts that would lead to blindness were operated on, despite a comparatively smaller number of affected persons a similar number of sighted life-years could be achieved throughout the world to that for patients with senile cataract. The partnership between the Rostock Ophthalmological Department and St. Joseph's Hospital in Kinshasa focuses on the analysis and treatment of avoidable blindness in children. Its main concern is the introduction of appropriate procedures for cataract surgery, in most cases combined with the implantation of injectable synthetic intraocular lenses. In the last 7 years about 600 procedures have been jointly performed, including 400 of congenital cataract, mostly bilateral.

Status of accommodative intraocular lenses

PURPOSE OF REVIEW

This review examines the recent peer-reviewed literature of the past 18 months, with the goal of providing an overview of the pseudophakic lenses designed to provide accommodative action. Accommodative lenses take advantage of axial movement, refractive change and bag filling to provide their effect. Single and dual optic design, as well as unique technologies, were reviewed.

RECENT FINDINGS

An overview is presented of the various accommodative lenses available for investigation and use. There is positive evidence that current accommodative intraocular lenses provide superior potential for near vision compared with standard intraocular lenses.

SUMMARY

The available data suggest that accommodative amplitude and pseudoaccommodation are both important factors in the functional ability of accommodative intraocular lenses to provide a range of distance, intermediate and near vision.

[New trends of customizing intraocular lens choice]

Definition and basic principle of customizing intraocular lens choice are described. The importance of the choicing intraocular lens for individual patient is illustrated. The review emphasizes that it is surgeon's responsibility to choice the appropriate intraocular lens for the best postoperative outcome and patient's satisfaction.

[Surgical treatment of cataract]

Today, the most frequently performed of all operative interventions is considered to be surgery for cataract. Modern surgical techniques applied under local anesthesia, tiny incisions that close spontaneously, reliable biometric methods, and the availability of artificial lenses, all combine to produce excellent results. In view of the low complication rate, this procedure can be recommended even in very old patients.

Wavefront-customized intraocular lenses

PURPOSE OF REVIEW

Recent advances in ocular wavefront measurement and in intraocular lens materials and manufacturing methods have brought cataract surgery to the brink of a period in which customized correction of higher-order aberrations with intraocular lenses may become standard practice.

RECENT FINDINGS

Retinal image quality in pseudophakic eyes is limited by the wavefront aberrations of the cornea and the intraocular lens. The Tecnis Z9000 is the first commercially available intraocular lens designed to account for the wavefront aberrations of the cornea, specifically spherical aberration. Clinical findings with the Tecnis Z9000 intraocular lens show improved contrast sensitivity at low and mid spatial frequencies. However, if the lens decenters or tilts modestly, higher-order aberrations are created, and the lens may underperform relative to standard intraocular lenses. At present, one firm is developing an intraocular lens that may be modified in vivo with near ultraviolet energy. Such a technology offers tremendous potential for a fully customized intraocular lens.

SUMMARY

Wavefront-customized intraocular lenses offer the promise of near perfect retinal image quality, such that only diffraction, chromatic aberration, retinal sampling and neural factors will limit vision in pseudophakic eyes.

US Trends in Refractive Surgery: 2002 ISRS Survey

PURPOSE

To determine the latest trends in refractive surgery in the United States.

METHODS

The full U.S. membership of the International Society of Refractive Surgery (ISRS) (approximately 900 members) was mailed the 2002 refractive surgery survey dealing with volumes, types, preferences of refractive surgery performed, and use of emerging technology.

RESULTS

Questions regarding RK, AK, PRK, LASIK, LASEK, intracorneal ring segments (ICRS), laser thermal keratoplasty (LTK), conductive keratoplasty (CK), phakic intraocular lenses (PIOL), and clear lens extractions (CLE) were examined in the survey. Procedure preference for low, moderate, and high myopia, and hyperopia, were compared with the results from the surveys of the previous 5 years. Preference for unilateral versus bilateral same-day surgery, laser type, and microkeratome choice were also compared with the survey data from previous years. Incidence and frequency of co-management of refractive surgery patients were compared with 1999-2001 data. New questions regarding pupil measurement/documentation, wavefront aberrometry, and custom ablations were incorporated into the 2002 survey.

CONCLUSIONS

As refractive surgery grows in the mainstream of ophthalmology, trends and changes in the United States continue to be elucidated by this professional organization survey. LASIK continues to dominate for refractive errors between -10.00 to +3.00 D. LASIK, LASEK, CLE, PIOL, and CK appear to have bright futures, whereas, RK, ICR, and LTK are on the decline. VISX continues to be utilized 2:1 over all other lasers combined, and instrumentation pupillometry is preferred 2:1 over pupil gauge cards. Currently, wavefront aberrometry and custom ablations are minimally employed but appear poised to be the wave of the future.

Treating with spectacle lenses: a novel idea!?

A design approach to low-vision device development-vision multiplexing-was introduced recently. This approach has been applied successfully to the design of novel electronic and optical low-vision aids. This paper discusses the application of the vision-multiplexing concept to spectacle lens design to address issues of low vision and to resolve problems of color discrimination and glare in driving. Because spectacles are considered a fashion accessory as much as they are a vision aid, cosmetic considerations are critical to the design of such aids. Spectacle-borne devices that are not concealed or attractive are unlikely to be used widely. Efforts to combine the functionality of vision multiplexing with improved appearance are illustrated.

Practice styles and preferences of ASCRS members--2000 survey. American Society of Cataract and Refractive Surgery

A survey of the practice styles and preferences of members of the American Society of Cataract and Refractive Surgery with a United States ZIP code was performed in August 2000. Approximately 26% (1400) of 5342 questionnaires mailed were returned prior to the november cutoff date. Three profile questions were used to cross-tabulate: age of the ophthalmologist, geographic location, and volume of cataract surgery per month. Current data were compared with data in previous surveys.

[The artificial lens: the folly of yesterday, the standard of today]

Traditional cataract operation (dislocation of the crystalline lens into the vitreous body by external pressure or by needling) is nearly as old as mankind. The idea of implanting an artificial lenticulus is not new but this was only performed for the first time in 1949. In the last 50 years, a better knowledge of corneal and retinal physiology, as well as the improvements of intraocular lens material and design, have led to very safe routine surgery.

Implementation of an innovation in the ophthalmic operating room: the Memory lens

I have participated in the evolution of the cataract procedure for the last 23 years. This year, as nursing director for an eye surgery center, I was responsible for the implementation of a new prerolled intraocular lens: The Memory lens. I review 5 implementation strategies, which are: Be open to recently approved products Utilize all company resources Introduce, train, train, train Evaluate, review, review, review Enjoy the questions and attention from others considering the innovation The implementation of this innovation confirmed both my and the operating room staff's ability to change and reaffirmed their commitment to achieve the resultant patient benefits.

Current trends in cataract and refractive surgery in Japan: 1997 survey

PURPOSE

A sixth annual survey was carried out by mail in January 1998, to investigate the current trends in cataract and refractive surgery in Japan.

RESPONDENTS

Questionnaires were sent to 816 ophthalmologist members of the Japanese Society of Cataract and Refractive Surgery. Data received from 409 (50.1%) of the recipients were cross-analyzed and compared with those from the previous surveys.

RESULTS AND CONCLUSION

In cataract surgery, there have been trends toward more surgical procedures performed by a surgeon, shorter period of hospitalization, and increased number of outpatient surgery. Ninety-two percent of respondents preferred phacoemulsification, 54% used the self-sealing wound-closure technique, and 19% used topical anesthesia for phacoemulsification. As for refractive surgery, surgeons remained rather conservative; with 28% and 7% of surgeons doing astigmatic keratotomy and refractive keratotomy, respectively. Photorefractive keratectomy, laser in situ keratomileusis, and phakic intraocular lens were judged to be useful refractive surgical procedures by 56.6%, 43.3%, and 25.1% of the respondents, respectively.

Practice styles and preferences of ASCRS members--1997 survey

A survey of the practice styles and preferences of members of the American Society of Cataract and Refractive Surgery with a United States ZIP code was performed in September 1997. Approximately 29% (1441) of the 5000 questionnaires mailed were returned by the November cut-off date. Three main profile questions were used to cross-tabulate data: age of the ophthalmologist, geographic location, and volume of cataract surgery per month. Current data were compared with data in previous annual surveys.

Cataract surgery in Australia 1985-94

BACKGROUND

Cataract surgery is the most common form of major ophthalmic surgery in Australia and a common surgical procedure among the elderly. The purpose of this report is to compile the numbers and rates of cataract extractions and implant of IOLs over the period 1985-94 for Australia.

METHODS

Data were obtained for public and private cataract extractions and IOL implants from state and territory ministries of health and from the Health Insurance Commission. The data relating to cataract surgery were compared with the growth in the proportion of elderly people in the population.

RESULTS

The number of cataract extractions has increased by 2.6 times over the ten-year period to 67,459 in 1994 and IOL implants have increased by 2.9 times over the same period to 70,084. The increase in the elderly population for the period was 1.3 times so that there is a relative doubling in the rate of surgery. The proportion of public patients has risen from 19% to 28% from 1985 to 1994.

CONCLUSIONS

The numbers of cataract extractions and IOL implants was increased at double the rate expected from the growth in the elderly population. Advances in microsurgery and IOL technology have resulted improved outcomes and have created a greater patient demand. The improved outcomes have also lead to ophthalmologists recommending cataract surgery at better visual acuity levels than previously.

Practice styles and preferences of ASCRS members--1995 survey

A survey of the practice styles and preferences of the 1995 members of the American Society of Cataract and Refractive Surgery with a U.S. ZIP code was performed in September 1995. Approximately 27% (1500) of the 5500 questionnaires mailed were returned by the December cutoff date. Four main profile questions were used to cross-tabulate data: age of the ophthalmologist, geographic location, volume of cataract surgery per month, and volume of refractive surgery per month. Current data were compared with data in previous annual surveys.

Practice styles and preferences of ASCRS members--1994 survey

A survey of the practice styles and preferences of the 1994 members of the American Society of Cataract and Refractive Surgery who had a U.S. ZIP code was performed in September 1994. Approximately 32% (1569) of the 4849 questionnaires mailed out were returned by the November cutoff date. Four main profile questions were used to cross-tabulate: age of the ophthalmologist, geographic location, volume of cataract surgery per month, and volume of refractive surgery per month. This report also compared the data with previously published surveys.

Current trends in the use of intraocular lenses in children

We present an overview of current practice patterns as they apply to intraocular lens (IOL) implantation in children. Two hundred and thirty-four members of the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) and 1,039 members of the American Society of Cataract and Refractive Surgery (ASCRS) responded to a questionnaire. Forty-six percent of AAPOS respondents and 27% of ASCRS respondents reported that they are currently implanting IOLs in children. Although the majority have implanted lenses in children older than six years, 16 AAPOS members and 41 ASCRS members reported implanting IOLs in patients in their first two years of life. Eighty-four percent of the respondents use the continuous curvilinear capsulorhexis technique of anterior capsulotomy in children. When a primary posterior capsulotomy is performed, 63 ASCRS surgeons (38%) reported using posterior continuous curvilinear capsulorhexis. Fixation of an IOL in the ciliary sulcus in a child was acceptable to 67% of the surgeons; however, 86% would not consider implanting an anterior chamber IOL in a child. Implications of the survey data are discussed.

Practice styles and preferences of ASCRS members--1993 survey

A survey of the practice styles and preferences of the 1993 ASCRS members with a U.S. ZIP code was performed in September 1993. Approximately 42% (1,786) of the 4,292 questionnaires sent out were returned prior to the December cut-off date. Three main profile questions were used to cross-tabulate: the age of the ophthalmologist, the geographic location, and the volume of cataract surgery per month. This report compares the data with previously published surveys of ASCRS members.

[Development of cataract surgery and implantation of artificial intraocular lenses in Czecho-Slovakia 1988-1992]

After a brief introduction on the history of implantations of synthetic intraocular lenses in Czechoslovakia the authors present an analysis of surgery of cataract and implantation of artificial intraocular lenses during the past five years in Czechoslovakia. The number of operations of cataract increases every year, a substantial increase was recorded in particular in 1992. During the other years there is also a change from intracapsular to extracapsular extraction of cataract and a slow onset of phacoemulsification. The number of departments where artificial lenses are implanted is increasing as well as the ratio of implantations in relation to the total of cataract surgery. In particular during the remaining three years a marked rise of implantation of posterior chamber lenses was recorded and a decline in implantations of iris-clip lenses. Almost 95% of implantations of posterior chamber lenses is considered satisfactory, while less than 60% implantations from the total number of cataract surgery is still insufficient.

[Implantation of a "pan-cameral" intraocular lens in Africa]

In modern medicine, extraction of the cataractous lens is followed by implantation of an artificial intraocular lens. The 2 main types of intraocular lenses, the anterior and the posterior chamber types, are essentially different in design. We present here 11 cases in which, due to lack of facilities, we were compelled to implant posterior chamber intraocular lenses in the anterior chamber of the eye. Postoperatively, visual acuity improved in 82% of the operated eyes.

Recent developments in refractive corneal surgery

The 4- and 5-year results of the Prospective Evaluation of Radial Keratotomy Study reveal a hyperopic shift of more than 1.0 D within the follow-up time in 22% and 24%, respectively, of the eyes that underwent radial keratotomy. The number of eyes with this complication increased progressively from 6 months to 4 years. Attempts to correct this progressive hyperopia are discussed. Results of clinical studies of myopic photorefractive keratectomy performed with the excimer laser are reviewed. Regarding safety and short-term efficacy, photorefractive keratectomy is a promising technique. In the past, corneal topography has been interpreted qualitatively. Ray-tracing analysis now allows quantitative estimation of the influence of aspheric corneas on the degradation of the retinal image. Three approaches to correct hyperopia, radial thermokeratoplasty, laser thermokeratoplasty, and hexagonal keratotomy are reviewed and discussed. Additional concave intraocular lenses for correction of high myopia are still undergoing clinical evaluation. Endothelial damage is the most dangerous short-term complication of implantation with these lenses.

Intraocular lenses

I have again reviewed the current state of the art in intraocular lens design in what has been a year of consolidation rather than dramatic discoveries. In foldable lenses, silicone reigns supreme, but there is the promising development of high-refractive-index foldable acrylic lenses. Heparin surface modification is now accepted as valuable in high-risk eyes, but there remains a question mark over surface passivation value. Small-incision lenses continue to proliferate with the design of new haptics to facilitate insertion after circular tear capsulorhexis. Some doubt has been raised concerning the optical qualities of ovoid lenses. Anterior-chamber myopic lenses for phakic myopic patients remain controversial. However, an increasing volume of data concerning their advantages and disadvantages is now available.

Practice styles and preferences of ASCRS members--1989 survey

A survey of the practice styles and preferences of 1989 ASCRS members with a U.S. zip code was performed in September 1989. More than 3,700 questionnaires were mailed and over 42% (1,543) were returned prior to the cut-off date. Three main profile questions were used to cross-analyze the results: the age of the ophthalmologist, the volume of cataract surgery per month, and the geographic location. This report also compared the data with previously published surveys of the ASCRS membership.

[From cataract eyeglasses to the artificial lens--changes in cataract surgery]

After a brief retrospective on the millennia-old technique of luxation of an opaque lens, the radical changes happening in the past 10 to 20 years to cataract surgery are outlined as follows: Microsurgical extracapsular cataract extraction and artificial intracular lens implantation. Some of the consequences for patient and physician are shown, particularly the criteria for undergoing surgery: cataract surgery should be performed whenever the cristalline lens opacities cause marked visual impairment to the patient.

The increasing frequency of surgery for cataract

The increasing frequency of cataract operation was investigated by examining the age related cataract extraction rates for Glasgow. Detailed analysis of case records of sample patients over the past decade was carried out to characterise trends in frequency of intraocular lens implantation, age of the patient at operation, preoperative visual acuity and rate of operation on the second eye. Between 1980 and 1987 the rate of cataract operation per thousand increased from 7.1 to 10.5 for patients aged 75 years and over and from 3.6 to 4.2 for those aged 65 to 74 years. There was a marked rise in the number of cataract operations relative to other eye operations between 1977 and 1988, from 19.3% to 37% and this increase was greatest in patients of 70 years and over. The same decade has seen intraocular lens implantation rise from 0% to 94.6% of cataract extractions. Visual acuity data show a significant trend towards operation at a better level of acuity in patients aged 70 years and over (p = 0.028) but not in younger age groups. There was no change in the visual acuity of the fellow eyes and no change in the frequency of operation on the second eye. It appears that cataract surgery is increasing more than can be predicted from the age of the population and this must be recognised in planning the future level of ophthalmology services.