SUMMARY

It is apparent that there are many flaws in the Helmholtz theory of accommodation. This is best exemplified by the fact that researchers have been unable to duplicate a variable-focus single lens system similar to the human crystalline lens. Furthermore, Helmholtz theory fails to have widespread applications to other scientific phenomena. In contrast Schachar’s theory not only has produced a variable-focus single element lens, but also has widespread applications to many different scientific disciplines. For example, the mechanism by which the human crystalline lens deforms during accommodation is similar in mechanism to the counterintuitive shape changes of the earth’s tides, the shape change of a drop of magnetic fluid within a magnetic field, and the similar but mysterious shape of many spiral galaxies that demonstrate central steepening and peripheral flattening.16 What it truly amazing is the impact that Schachar’s theory will have on the camera industry, defense industry (focusing on targets), optical computers and astronomy.

The visual correction revolution currently appears to be complete. Given the concept that presbyopia is a surgically correctable condition, the last major hurdle in refractive surgery has been overcome. While not everyone in the world needs glasses to see at distance, 100 percent of the population over the age of 40 will eventually need correction for presbyopia. The global impact of this immense population will be a driving force for the continued research and development of this procedure.

The anatomical modifications that scleral expansion bands produce in the ciliary muscle and trabecular meshwork may make this the procedure of choice for primary open-angle glaucoma. It is interesting to speculate the impact that SRP will have by allowing accommodation to continue during aging on the cataract prone crystalline lens.

REFERENCES

1.von Helmholtz H: Uber die akkommodation des auges. Albreckt von Graefes Arch Ophthalmol 1885;1:89.

2.Fincham E: The mechanism of accommodation. Br J Ophthalmol 1937;8:1-9.

3.Schachar RA, Cudmore DP: The effect of gravity on the amplitude of accommodation. Ann Ophthalmol 1994;26: 65-70.

4.Koomen M, Tousey R, Scolnik R: The spherical aberration of the eye. J Opt Soc Am 1949;39:370-76.

5.Brown N: The change in shape and internal form of the lens of the eye on accommodation. Exp Eye Res 1973;15: 441-59.

6.Rafferty NS: Structure, function and pathology. In Maisel H (Ed): The Ocular Lens: Marcel Dekker: New York 1985;2-5.

7.Atchison DA: Accommodation and presbyopia. Ophthalmic Physiol Opt 1995;15:255-72.

8.Kaufman PL, Rohen JW, Barany EH: Hyperopia and loss of accommodation following ciliary muscle disinsertion in the cynomolgus monkey—physiologic and scanning microscopic studies. Invest Ophthalmol Vis Sci 1979;18: 665-73.

9.Tamm S, Tamm E, Rohen JW: Age-related changes of the human ciliary muscle—a quantitative morphometric study. Mech Ageing Dev 1992;62:209-21.

10.Schachar RA: Cause and treatment of presbyopia with a method for increasing the amplitude of accommodation. Ann Ophthalmol 1992;24:445-52.

11.Schachar RA: Zonular function—a new hypothesis with clinical implications. Ann Ophthalmic 1994;26:36-38.

12.Schachar RA, Anderson DA: The mechanism of ciliary muscle function. Ann Ophthalmol 1995;27:126-32.

13 Schachar RA: Histology of the ci1iary muscle-zonular connections. Ann Ophthalmol 1996;28:70-79.

14.Schachar RA, Cudmore DP, Black TD: A revolutionary variable focus lens. Ann Ophthalmol 1996;28:11-28.

15.Schachar RA, Cudmore DP, Black TD et al: Paradoxical optical power increase of a deformable lens by equatorial stretching. Ann Ophthalmol 1998;30:10-18.

16.Schachar RA: Is Helmholtz’s theory of accommodation correct? Ann Ophthalmol 1999;31:10-17.

17.Schachar RA: In vivo increase of the human lens equatorial diameter during accommodation. The American Physiological Society 1996;R670-76.

18.De la Garza Vi, Jose: Personal communication and notes.

19.Cross W: Personal communication and notes.

20.Yee R: Personal communication and notes.

21.Maistre JP: Personal communication and notes.

22.Zdenek G: Personal communication and notes.

23.Lothringer L: Personal communication and notes.

24.Schachar RA: Personal communication and notes.

25.Schachar RA: Treatment of Presbyopia and Other Eye Disorders 1994.

Jerome Jean Bovet (Switzerland)

INTRODUCTION

Concept

Removal of the crystalline lens before the vision decrease because of opacity offer many advantage to any refractive surgery or clear lens extraction.The concept of catarefractive surgery is different to refractive lens exchange because you wait that you can see a touch of cataracte. The advantage that you can prepare your patient of different technique like monovision, multifocal lens, correction of the astigmatisme or induce an astigmatisme because the overall spherical aberration of the human eye increase with advancing age, this is the result of increasing lenticular aberration. This implies that if you correct high order aberration by corneal surgery, you will lose this effect at a later date by cataracte surgery once the patient developed a cataract it is more difficult to test the patient, if it will be a good candidate for a catarefractive surgery and the surgery will be more approximative.

Bimanual Micro-phaco

Why should we carry out phakonit bimanual micro– surgery instead of conventional 3 mm phacosurgery? When starting work on a new procedure, it is always difficult to decide, when problems arise, whether to stop or to continue. First, to do a microincision without a special lens is of little use because you will need to enlarge your incision to 3 mm or do another incision. The interest in starting to work with microincision phaco at the moment arises from the fact that a new, foldable lens

has been developed that can be inserted into an incision between 1.5 to 1.7 mm. Also, the benefit of using such a small incision is that we can be sure that there will be no shift to astigmatism later. When we examine the results of cases up to now, we see shifts of at least one dioptre after cataract surgery. If this shift can be avoided, we will have better results with multifocal lenses, because we need less than one dioptre to maximise and utilise all their potentials.

HISTORY

Bimanual Phaco

To know who start the bimanual procedure we have to come back quite late the first which work with bimanual was de Dardenne in Bonn Germany he has the first the idea to take out the crystalline of a baby with a bimanual aspiration irrigation, Brauweiller1 come back with the technique with phaco and bimanual aspiration irrigation which is far more easier than with the monocanula. 1982 Steven P Shearing2 start to do phacoemulsification bimanual with a sleeveless tip. Amar Agrawal3 in India and Stunoeka4 in Japan restart the technique of bimanual micro-phaco, the reason the technique start this time that we found new lens which can be insert under an incision of less than 2.8 mm.

Astigmatisme Keratotomy

About history of refractive surgery Fiedorov in 1970 give to ophthalmologist. The radial keratotomy technique because of the continuous hyperopic shift the method stop to be the major method for refractive correction but the astigmatisme keratotomy is still used because this method stay stable overtime and it is a good compromise to correct little astigmatisme5 till three dioptries without any problem, with the development of the excimer the radial keratotomy disappear leaving the astigmatisme keratotomy (Fig. 32.1 and 32.2)

Catarefractive Diagrams (Table 32.1 and 32.2)

Cataracte and refractive surgery6 englobe all the different

Tables 32.1 and 32.2: Catarefractive diagrams

previous notion that we work with. We have three main subjects cataracte, accomodation, and refractive surgery. All this concept we need to achieve the catarefractive surgery for exemple if you do not use an astigmatisme correction like AK or lasik your multifocale lens will never

Figure 32.1: Mark before the AK4

Figure 32.2: AK with a diamond knife 600 micron depth

work and so you will loose your pseudoaccommodation correction, the catarefractive surgery concept is larger than prelex because you have to integrate more notion to obtain your goal. Catarefractive surgery integrate fully the notion of bimanual micro-phaco because to correct and to assure no astigmatism in the long-term you have to do your catarefractive surgery with a bimanual microincision of less of 3 mm catarefractive surgery is used at any age for hypermetropique eye more than three dioptries, after the age of 50 all the emmetropique and miopique eye.

Preoperative Exams

To start the concept of catarefractive surgery we have to do routinely an refraction with and without cycloplegia even the patient is older than 50 to be sure to find all the residual ammetropia.

To test7 if the patient will support a monovision correction it is very easy to try if the patient will able to support a +1.5 dioptries of one eye. It is very important to use an accurate systeme of biometry if you do not use the Zeiss IOL master we strongly suggest to use your ultrason tip with the prägershell added.

Pachymetry is important if we want to finish the procedure with a lasik and at the end topography to be sure that you have not a frust keratoconus.

Figure 32.3: Instruments

The technique we general use for a right eye is under topical anesthesia with the Gills8,9 technique we do a 1 mm paracentesis at 4’ o’clock and a 1.2 mm incision with a flat knife at 2 o’clock we will enlarge later on for the lens. We always control the width of the incision we always have to remember that the diameter is not the circumference and the relation is C = 2π r with this relation more the diameter come little more the constant in relation is big π= 3,14 for a diameter of 1 mm the circumference is 3.14 mm and the cornea is not extensible like the scleral tissue.

Injection of acid hyaluronique,and capsulorhexis with a double curve forceps (Fig. 32.4). You have to try many different forceps to find your cup of tea the most rigid, straight on used for vitrectomies are the worst, my best choice are the double curve first from the top (Fig. 32.6). The difference with a conventional phaco is the sleeveless tip, the diameter of the bimanual irrigation-aspiration and the injector with a new cartridge which permit to inject the lens without going inside the anterior chamber with the cartridge.

Bimanual micro-phaco technique change with the hardness of the cataracte we use most of the time for a 2+cataracte a irragating Nagaharra chopper and we use a phacochop technique.10,11 To succed to your

bimanual micro-phaco12 (Fig. 32.7) you have to change your fluidic system you have to change the diameter of your irrigation from 20 gauge to a 19 gauge to increase the input in the anterior chamber the flow rate of the output as to be increase to 38 to 40 cc/min to cool down the phacotip, the paracentesis have to be 1 mm and for the phaco tip of 1.2 mm (Fig. 32.5). To have the same efficacy during the phacotime we have to increase the vacuum to a level of 300 to 500 mmHg. You have to play with the pedal like with the pedal of a piano not to give to much and to longer phacopower if you don’t want to burn your cornea. To increase momentaly the flow which facilitate the aspiration of fragment of

the nucleus you can use an air pump connected to your BSS bottle to increase the pressure which increase the flow.13

Only a few lens14-16 can be injected through an incision less than 2 mm (Fig. 32.8) for this purpose you have to put end to end the cartridge and the corneal incision, then we have to shoot the lens like suppository inside the anterior chamber, we use most of the time the Acrismart 36 or 48 because of its stability and its accuracy with our biometry. The lens Acrismart from Acritec is a acrylic hydrophilic-coated hydrophobic platelette lens. This lens has a very good reaction and the placement inside the bag is optimal (Fig. 32.9).

Astigmastime Keratotomy

Once we have finish the cataract operation, we correct the astigmatism with an AK astigmatisme keratotomy.6 We use the Gill’s normogram at the steepest meridian with a diamond knife of deepest of 600 micron to correct one dioptries of astigmatisme we do a two incisions at the limbus of 6 mm at the steepest meridian.

Monovision versus Multifocal

To correct the presbyopia17, 18 the only technique we have to test the patient before the operation is the monovision which can also be a “multifocale vision with two eyes” the visual brain has to choose which image is treated the one for near or the one for distance and the selection of the patient are very easy. We just have to add from one eye or the other an addition of +1.5 to know if the patient is a true alternate he will have no pain or no disagreement the other patient can not be correct with this technique.

To have more comfort during night we have to prefer the lens which are prolate or aberrated corrected. At the end if we did not reach the goal we can do a lasik7 after a delay of three months to be sure that the vision is stabilize.

EXAMPLE CASE REPORT

W female 54 yr old

BCVA RE 07 –2.5-0.5/0 LE 0.5 –3.5 –1.5/160

Intervention catarefractive surgery

Bimanual micro-phaco insertion incision 1.7 mm +AK 2 incision at the limbus 5 mm arcuate

RE Acrismart 36 A 16.5 D LE Acrismart 36A 15.5D+AK

Binoculare vision UCVA 0.8

Binoculare vision for near 0.5 Birkhauser at 20 cm

CONCLUSION

Bimanual Micro-phaco

Remember your physics for your incision 2π R =C Select your right instruments: for your 2 parencentesis, for your irrigating choper, phaco tip as to be 0.9 mm diameter.

Increase irrigation 36 mm/min + air pump Reduced ultrasound with your foot pedal Take your time, time consuming.

Catarefractive Surgery

In conclusion to use the catarefractive technique you have to carefully select your patient.

You can take out the crystalline of any hypermetropique patient with more than 3 dioptries after the age of 20 year old.

You can use this technique with the myopique patient older than 45 years old and with more than 4 dioptries.

You have to test the monovision before you do the procedure and if you want to have a full success you have to correct the astigmatisme.

To be very accurate wait 3 weeks before to do the second eye.

REFERENCES

1.Brauweiler P. Bimanual irrigation/aspiration. J Cataract Refract Surg-Oct 1996;22,(8):1013-6.

2.Sharing SP, Releya RL,Loiza A,Shearing RL. Routine phacoemulsification through a one-millimeter non sutured incision Cataract 1985;2:6-10.

3.Agarwal A, Agarwal A, Agarwal S, Narang P, Narang S. Phakonit: phacoemulsification through a 0.9 mm corneal incision. Journal of Cataract and Refractive SurgeryOctober 2001;27(10):1548-52.

4.Tsuneoka H, Shiba T, Takahashi Y. Feasibility of ultrasound cataract surgery with a 1.4 mm incision. Journal of Cataract and Refractive Surgery 2001;27(6) 934-40.

5.Gills JP, Van Der Karr M, Cherchio M. Combined toric intraocular lens implantation and relaxing incisions to reduce high preexisting astigmatism. Journal of Cataract and Refractive Surgery-September 2002;28(9):1585-88.

6.J Bovet. Cataract in clear cornea by phacoemulsification and correction of astigmatism by AK. Indian Academy of Ophthalmology Advances in ophthalmology, Mumbai 1998.

7.J Bovet, A Chiou, C de Courten, P Rabineau, O Achard. Bioptic. ESOPES, KSMG, Tunis life april 2000.

8.J Bovet, JM Baumgartner, JC Bruckner, V Ilic, O Achard. L’anesthésie topique en chirurgie oculaire et sa préparation.

In: Les Dimensions de la douleur en ophtalmologie A.B. Safran, T. Landis, P. Dayer eds Paris Masson, 1998;16673.

9.Fenzl RE, Gills JP. Intracameral lidocaine in routine phacoemulsification. Ophthalmology 2000;107(10): 1803-04.

10.Sullivan BR. Phaco chop: Mastering techniques, optimizing technology, and avoiding complications. American Journal of Ophthalmology 2004;138(4):707.

11.Metha KR. The new phaco cleaves techniques for hard cataracts. J intraocular Implant and Refractive Society India 1996;1:74-75.

12.J Bovet, O Achard, JM Baumgartner, A Chiou, C de Courten, P Rabineau. Bimanual Phaco Trick and Track. ASCRS-ASOA Film San Diego 2004;1-5.

13.Vejarano LF, Tello A, Vejarano A. Phakonit: Incisions and use of a pressurized inflow system. Journal of Cataract and Refractive Surgery 2004;30(5):939.

14.J Bovet, O Achard, JM Baumgartner, A Chiou, C de Courten, P Rabineau. 0.9 mm Incision Bimanual Phaco and IOL Insertion Through a 1,7 mm Incision. Symposium on cataract,IOL and refractive surgery abst ASCRS-ASOA San Francisco april 2003;12-16.

15.Agarwal A, Agarwal S, Agarwal A. Phakonit with an AcriTec IOL. Journal of Cataract and Refractive Surgery 2003;29(4):854-55.

16.Dogru M, Honda R, Omoto M, Fujishima H, Yagi Y, Tsubota K. Early visual results with the rollable ThinOptX intraocular lens. Journal of Cataract and Refractive Surgery 2004;30(3):558-65.

17.Chiou AGY, de Courten C, Bovet J. Pseudophakic ametropia managed with a phakic posterior chamber intraocular lens. J Cataract Refract Surg 2001;27:1516-8.

18.Steinert RF, Post CT, Brint SF, Fritch CD, Hall DL, Wilder LW, Fine IH, Lichtenstein SB, Masket S, Casebeer C, et al. Ophthalmology 1992;99(12):1752/PMID:1480385.

I Howard Fine

Richard S Hoffman

Mark Packer (USA)

INTRODUCTION

Although the Acri.Tec (Berlin, Germany) and the ThinOptx (Abingdon, VA) IOLs have both been utilized in clinical trials in Europe and Asia, their results are still uncertain with respect to stability of refraction and possible deformation of these lenses under the forces of capsular bag constriction. However, there is on the horizon new technology that may be very promising.

Calhoun Vision (Pasadena, CA), which has produced the Light Adjustable IOL, is capable of providing an injectable polymer with light adjustable technology. This is one of several companies that are working with injectable technology (Fig. 33.1). The problem with these efforts resides in the fact that it requires a lens extraction through an approximately 1 mm capsulorhexis, and this indeed is very difficult to do. Although the Advantecs (cataract system) was tested by Bausch & Lomb (San Dimas, CA) and was capable of clear lens exchange through such small incisions that technology is currently on hold. We have experimented in our own surgery center on 1 mm capsulorhexis clear lens extractions in cadaver eyes and have found it to be technically extremely formidable and unpredictable. However, the promise of light adjustability, allowing sequential adjustments, for which Calhoun holds the patents, would make this type of approach extremely appealing. The problems of posterior capsule opacification also will have to be addressed since fluid injectable polymers would leak into the vitreous chamber if a posterior YAG laser was necessary.

Figure 33.2: Schematic rendering of insertion of a Smart IOL

Another model of a futuristic IOL that offers perhaps even more promise is the Smart IOL by Medennium (Irvine, CA). The Smart IOL is a thermodynamic hydrophobic acrylic IOL that is designed to completely fill the capsular bag, but is convertible at room temperature to a thin rod, which can be injected through a very small incision. Under the influence of body temperature, the lens reconstitutes to its initial size, shape and imprinted dioptric power (Fig. 33.2). This lens would not only fill the capsular bag but become adherent to it because it is a hydrophobic acrylic, which becomes

covered, soon after implantation, with fibronectin, a naturally occurring bio-adhesive (Fig. 33.3). We think that because of its high refractive index and its stable gel configuration at body temperatures, this is an extremely desirable technology. With its high refractive index, minute changes in the shape of the lens would result in large amplitudes of accommodation. Also of importance is that it could include light adjustable technology which would give us the ability for sequential adjustment over time as subtle changes in the patient’s refractive error occur.

The future for micro-incision IOLs is extremely bright and I think although at this time we can only look at extensions of existing technology, I believe break through technology will be on the horizon very soon.

A

Advantages of lens based refractive surgery 3

Advantages of phakic IOLs 55 Akkommodative 1 CU IOL 146 Amblyopia 61

Angular-support anterior chamber phakic lenses 4

Anterior chamber phakic IOL implantation 83

Artiflex 87

artiflex complications 89 artiflex future 89

artiflex refractive results 89 artiflex surgery 88

Artisan lens 6

Assessment for refractive lens surgery 2 postoperative 2

preoperative 2 Astigmatism 131

Astigmatism keratotomy 238, 241 Axial length measurements 31

B

Bimanual micro-phaco 237 Bimanual phaco 238 Bioptics 56

C

Calhoun vision 176 Catarefractive surgery 237 Combined astigmatism 61

Complications of angle fixated phakic IOLs 47

Complications of anterior and posterior chamber IOLs 84

Complications of foldable intraocular lenses 160

bag sulcus fixation 161

capsular bag distension syndrome 162

capsular contracture syndrome 162 Descement’s membrane detachment

160

endophthalmitis 162 glare 161

IOL damage during insertion 161 IOL decentration 161

lens dislocation 161

posterior capsule opacification 162 Complications of LASIK 24 Complications of phakic IOLs 141

complications of anterior chamber angle supported phakic IOLs 141 endothelial complications 141 other problems 143

quality of vision issues 143 size-related complications 141

complications of iris-supported phakic IOLs 143 complications related with the

IOL 143

long-term complications due to poor surgical technique 143 complications of posterior chamber

phakic IOLs 144

Contact crystalline lens/implant 40 Contraindications for RLS 2 Corneal ectasia 26

Corneal surgery for myopia and hyperopia 18

Crystalens refractive lens 184 Cycloplegia 239

E

Emmetropia 30

Enclavation 93

Endothelium safety distance 40

F

Foldable anterior chamber phakic IOL 82

Fourth generation lenses 6 Futuristic lenses 243

H

Helmholtz’s theory 223

High hyperopia 198 High myopia 197

History of refractive lenses 1 Humanoptics accommodating IOL 146

biometry 147 mechanism of action 147 post-operative care 148 surgical technique 147

Humanoptics injector 147 Hyperopia 131

refractive correction of myopia 95 surgical technique 92

I

ICU IOL 199

Ideal pseudophakic lens 170 Implantable contact lens 8 Implantation of TPIOLs 131

complications 135 conclusion 131 methods 131

patients and methods 132 results 131, 133

Indications for refractive lens surgery 2 Iridectomy 63

Iridocyclitis 70

Iris claw fixation technique 90 Iris claw Verisyse phakic IOL 90

calculation of refractive power of lens 95

complications 94 contraindications 94 lens design 90

minimum requirements 92 operation 92

anesthesia 92 postoperative examinations 95 postoperative medication 95 preoperative evaluation 92 preoperative management 92 range of correction 92

refractive correction of myopia 95 surgical technique 92