Hyperopia and presbyopia - part 8 pot

If the blade is easily Figure 12 The lamella diamond blade being used to make a scleral belt loop... 229 The Scleral Expansion ProcedureFigure 13 The thickness of the scleral belt loops

228 Phillips and Yee

Figure 11 The 5-mm lamella diamond blade

parallel to each other, not radial to the limbus If the incisions are not parallel, the segmentmay rotate within the incision losing most of its lift Care should be taken to remove all

of Tenon’s capsule near the incision so as to avoid a shallow incision

Without losing scleral fixation, a 5-mm-long 1.5-mm-wide lamella diamond blade(Fig 11) is placed in the incision located furthest from the scleral fixator The diamondblade is slowly advanced through the sclera toward the other incision near the scleralfixator (Fig 12) By observing the relative visibility of the lamella diamond blade throughthe sclera, one controls the depth of the blade The very tip of the diamond lamella bladeshould not be visible as the blade is passed through the sclera Only a slight elevation orbulge of the sclera at the lateral edges of the blade should be seen If the blade is easily

Figure 12 The lamella diamond blade being used to make a scleral belt loop

229 The Scleral Expansion Procedure

Figure 13 The thickness of the scleral belt loops and the exit wound are checked with the mm-wide spatula

1.4-seen through the sclera, then the loop is too shallow and the effect of the surgery will begreatly reduced In making the scleral belt loop, care should be taken not to retract andadvance the blade unnecessarily to avoid making blind pockets that will increase thedifficulty of passing the scleral expansion segment

On nearing the exit incision with the diamond blade, the sclera is depressed withthe scleral fixator to help open the exit incision It is usually necessary to aim the lamellablade upward just before exiting to prevent a blind pocket under the exit incision Theentire lamella diamond blade is 5 mm long The front curve of the blade is 1 mm long.Therefore, by seeing the complete front curve of the blade, the surgeon is assured thatthe scleral belt loop is no longer than 4 mm

In removing the lamella diamond blade, the surgeon must maintain fixation withthe scleral fixator and remove the lamella blade slowly and in a controlled manner Indoing so, the surgeon avoids cutting the edges of the entrance incision, avoids perforatingthe belt loop, and ensures that the blade is not passed into the suprachoroidal space Ifthere is any doubt that the lamella blade is completely passed through the exit incision,test the incision using a 1.4-mm-wide spatula (Fig 13) It should be possible to readilypass the spatula through the incision in the same direction that the scleral expansionsegment will be passed

The four scleral expansion segments (Fig 14A and B) come packaged in much the sameway as an intraocular lens (IOL) Prior to grasping the segments, place one or two drops

of sterile saline into the well holding the segments This prevents loss of the segmentsdue to static electricity Either a specifically designed scleral expansion segment holder

or the injector can be used to pass the segment through the scleral belt loop (Fig 15).Load the segment into the injector or segment holder curved side up Without moving thescleral fixator, the segment is passed into the scleral belt loop In difficult cases it is

230 Phillips and Yee

Figure 14 (A and B) The dimensions of the segment

sometimes necessary to pass the segment upside down and then rotate the segment intoplace using the injector and heavy needle holder Rotation of the segment will stretch thebelt loop, but a slightly stretched belt loop will produce a greater effect than a thin beltloop If it is still not possible to pass the segment, the segment may be getting caught in

a blind pocket Reapply the scleral fixator at the opposite end of the tunnel and try passingthe segment in reverse by beginning at the exit side of the scleral belt loop

If the patient suddenly moves or complains of eye pain, immediately stop advancingthe segment This may indicate that the vitreous, subchoroidal space, or ciliary body hasbeen entered This can be confirmed by the presence of vitreous or fluid containing blackpigment exiting one or both ends of the scleral belt loop At this point, the segment should

be removed and the eye examined If the surgeon feels it is safe, it may still be possible

to pass the segment upside down from the other direction

If the scleral belt loop is torn or severed, remove the segment and close the sclera.The operation may be completed after the sclera is healed in 2 or 3 months

Figure 15 Placement of the segment

231 The Scleral Expansion Procedure

Sutures are placed at the 12:00 and 6:00 o’clock meridians by passing the suture throughthe conjunctiva and back out through the sclera and burying the knot The corners of theconjunctival incision should be overlapped Finally, administer 20% mannitol (1 g/kg)intravenously over 30 min to avoid malignant glaucoma

The pupils should be checked for reactivity and pupil size An irregular or dilated pupilmay suggest AIS or sector AIS If a pupillary abnormality is noted, place one drop of0.5% pilocarpine in each eye Pupillary constriction provides evidence that adequate ante-rior segment blood flow is present The sine qua non for AIS is a dilated nonreactive pupil

or a nonreactive pupillary sector Other signs of AIS are nausea, an intraocular pressure(IOP) less than 10 mmHg, corneal edema and folds, and anterior chamber cell and flair(Fig 16) At this point some recommend that the segment or segments causing AIS beimmediately removed Others recommend giving the patient an additional dose of intrave-nous manitol and 2 to 4% pilocarpine every 5 min for a total of six times in addition tooral or intravenous steroids and aspirin if not contraindicated (21) If the pupil does notrespond in 2 h, repeat the manitol and six doses of pilocarpine (21) If there is still noresponse after another 2 h, the segments should be removed

Artificial tears, topical antibiotics, and topical anti-inflammatory or nonsteroidalagents should be administered postoperatively It is recommended that topical antibioticsand anti-inflammatory eye drops be used for 2 weeks Any remaining sutures should beremoved after 10 to 14 days Artificial tears should be used frequently and a bland ointmentadministered at night for at least 3 months

Some patients complain of a mild to severe brow ache beginning about 30 min aftersurgery and lasting 2 to 6 h It may be necessary to treat these patients with analgesics

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far rather than far to near Patients should hold an eye chart 4 in (10 cm) from their eyeand look at the smallest line they can see Patients are then asked to concentrate until theycan see any letter on the next smaller line Next they should hold fixation on the letter

on the smaller line and slowly move it away from the eye until it is at full arm’s length.The eye chart can then be brought slowly back toward the eye while continuously holdingfixation on the smaller line until the eye chart is back at 10 cm from the eye Once theycan read all the letters on that smaller line, have them move to the next smaller line andagain move the eye chart to arm’s length while maintaining fixation on the smaller line,and so on Patients should repeat this exercise as frequently as possible, but for at least

10 repetitions, four times a day, each time trying to fixate on a smaller line beginning atthe close distance of 10 cm from the eye It is much better to do frequent exercise sessionsthroughout the day than one long session Following the exercises, patients will noticethat they can read better Patients will usually experience ciliary pain during the exercisesfor the first 2 weeks after surgery The patients can be told that this pain is a good signand that the exercise is strengthening their ciliary muscles Patients should avoid the use

of a near vision optical aid during their daily reading tasks Additionally, patients shouldsquint as little as possible during the eye exercise; if they initially have difficulty perform-ing their daily reading tasks, encourage them to use a bright light or, only if absolutelynecessary, to squint in order to avoid the use of a near optical aid As they continue theeye exercise, the requirement to squint or use a bright light during their daily readingtasks will decrease

Only one case of AIS has been reported using the latest 5.5-mm scleral expansion segments(23) This complication may have resulted from improper positioning of the segments(23) One case of endophthalmitis has also been reported (23) This case was thought toresult from a break in sterile technique (23) Additionally, one case of scleral thinningsimilar to that observed with scleral buckles has been reported and may have been a result

of scleral expansion (24) To date, no cases of malignant glaucoma have been reportedusing the new scleral expansion segments Theoretically, this is a possibility, as the seg-ments may increase posterior pressure, blocking outflow and resulting in aqueous misdirec-tion Intravenous manitol is given to dehydrate the vitreous decreasing the likelihood of thiscomplication Other minor complications include conjunctival hyperemia, subconjunctivalhemorrhage, transient ptosis, rotation or subluxation, of the scleral expansion segments,photophobia due to tear film instability, conjunctival erosion, accommodative fatigue,temporary keratoconjunctivitis, swollen or irregular conjunctiva, and astigmatism, whichmay last for 2 to 3 months and but subsides with intense treatment with artificial tears

Increases in accommodation after this technique have ranged from 1.00 to 10.00 D (13).Two different studies (20) of 29 and 7 patients have reported an increased range of accom-modation in all patients, with an average of 3.02 and 3.13 D respectively Similar to ourfindings, an increased range of near vision was also noted in the unoperated eye Thisincrease approached 20 to 50% of the increase measured in the operated eye

233 The Scleral Expansion Procedure

Scleral expansion has been successfully performed after LASIK, PRK, and RK Withregard to LASIK, however, it is easier to perform LASIK before scleral expansion due

to difficulties that may be encountered while applying the suction ring Scleral expansionhas been performed as early as 6 weeks post-LASIK Obviously, PRK and laser epithelialkeratomileusis (LASEK) are good alternatives for patients who have had previous scleralexpansion procedures

Several other methods have been used to expand the sclera Some surgeons have madesimple scleral incisions with a diamond knife to expand the sclera The scleral incisionsare limited to an accommodative range of only aboutⳭ1.50 D, and, as the incisions heal,the effect declines (R Schachar, personal communication, 2001) In order to prevent theincisions from healing, Fukasaku has inserted silicone plugs into the scleral incisions (24a).The infrared laser has also been used to make deep scleral incisions (25) The averagecorrection is also limited to an accommodative range of aboutⳭ1.50 D and will likelyregress with time (R Schachar, personal communication, 2001) In contrast to the above,Lin has described no regression after scleral expansion using infrared laser (J Lin, personalcommunication, 2001) A major concern with the infrared laser is that it can coagulateblood vessels and lead to anterior segment ischemia There have been two phthisical eyes

as a result of making scleral incisions with the infrared laser for the treatment of presbyopia(R Schachar, personal communication, 2001) Last, as a result of the deeper tissue ablation,the potential for rupture after blunt trauma is also a concern

While chronic open-angle glaucoma is a genetic disease, predisposed patients may benefitfrom scleral expansion due to anatomical modifications produced by the procedures inthe ciliary muscle and trabecular meshwork (26,27) International clinical trials evaluatingscleral expansion for the treatment of ocular hypertension and primary open-angle glau-coma in Canada and Mexico have demonstrated excellent preliminary results (27,28) Themedian decrease in IOP after scleral expansion was 7 mmHg, and the postoperative de-crease in IOP appears to be equivalent to the IOP-lowering effect of the preop, physician-prescribed topical glaucoma medications (27)

Scleral expansion is a new procedure designed to treat presbyopia surgically While thetheory on which it is based continues to be a subject of intense debate, it must be notedthat patients report an improved ability to read at near after scleral expansion Given theimmense impact of presbyopia, surgical reversal of presbyopia will likely continue to be

an area of significant interest In addition, scleral expansion may offer a new modalityfor the treatment and prevention of ocular hypertension and primary open-angle glaucoma

If scleral expansion is found to effectively decrease IOP, the adverse reactions and systemicside effects commonly observed with glaucoma medications could be avoided and potentialsurgical filtering and shunt procedures could be delayed or eliminated

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ACKNOWLEDGMENT

The authors would like to thank Presby Corp for their assistance in writing this chapterand the illustrations they provided Additionally, we would like to thank Dr Adrian Glasserand Dr Ronald Schachar for their comments

7 Fincham EF The mechanism of accommodation Br J Ophthalmol 1937; 8(suppl):5–80

8 Stuhlman O An Introduction to Biophysics New York: Wiley, 1948:106–107

9 Schachar RA The mechanism of accommodation Int Ophthalmol Clin 2001; 41:17–32

10 Schachar RA Histology of the ciliary muscle-zonular connections Ann Ophthalmol 1996;28:70–79

11 Schachar RA, Tello C, Cudmore DP, Liebmann JM, Black TD, Ritch R In vivo increase ofthe human lens equator diameter during accommodation Am J Physiol (Regul Integr CompPhysiol 40) 1996; 271:R670–R676

12 Schachar RA, Anderson DA The mechanism of ciliary muscle function Ann Ophthalmol1995; 27:126–132

13 Schachar RA, Black TD, Kash RL, Cudmore DP, Schanzlin DJ The mechanism of dation and presbyopia in the primate Ann Ophthalmol 1995; 27:58–67

accommo-14 Schachar RA Zonular function: a new hypothesis with clinical implications Ann Ophthalmol1994; 26:36–38

15 Schachar RA, Cudmore DP, Black TD Experimental support for Schachar’s hypothesis ofaccommodation Ann Ophthalmol 1993; 25:404–409

16 Schachar RA Cause and treatment of presbyopia with a method for increasing the amplitude

of accommodation Ann Ophthalmol 1992; 24:445–452

17 Yang GS, Yee RW, Cross WD, Chuang AZ, Ruiz RS Scleral expansion: a new surgicaltechnique to correct presbyopia Invest Ophthalmol Vis Sci 1997; 38(suppl):S497

18 De Smet MD, Carruthers J, Lepawsky M Anterior segment ischemia treated with hyperbaricoxygen Can J Ophthalmol 1987; 22:381–383

19 Jampol LM Oxygen therapy and intraocular oxygenation Trans Am Ophthalmol Soc 1987;85:407–437

20 Cross WD, Zdenek GW Surgical reversal of presbyopia In: Agarwal S et al, eds RefractiveSurgery New Delhi: Jaypee Brothers Medical Publishers, 2000:592–608

21 Cross WD Scleral expansion band technique treats presbyopia Ocul Surg News 2001; 19:28–34

22 Ruelas V Optometric postoperative care In: Schachar RA, Roy FH, eds Presbyopia: Causeand Treatment The Hague, The Netherlands: Kugler, 2000: 105–107

23 Zdenek G Complications in surgical reversal of presbyopia can be avoided, managed OculSurg News 2001; 19:39–44

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24 Singh G, Chalfin S A complication of scleral expansion surgery for treatment of presbyopia

is familiar to the ophthalmic surgeon, since we are performing this technique for cataractpatients for many years We could learn most results of multifocal IOLs from our cataractpatients.

1 Cataract Surgery as Refractive Surgery

When the IOL was introduced, both patients and the surgeons were impressed by theresulting relatively good vision without spectacles or contact lenses Recently, cataractsurgery has been accepted as refractive surgery, since we can correct preoperative myopia

or hyperopia at the time of surgery Even clear lens extraction following IOL implantation

is accepted for the treatment of extreme myopia or hyperopia An ideal IOL would beone that would replace the original crystalline lens at younger age We can correct notonly preoperative refractive error but also age-related presbyopia

2 Impression of the Multifocal IOL

When the multifocal IOL was first introduced, we expected it to act like bifocal spectacles,

so that the patient would have clear vision at far and near The results with first-generationmultifocal IOLs were somewhat disappointing, however, since the distance visual acuity

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was dependent on pupil size and sometimes inferior to that with monofocal IOLs Anotherconcern is the loss of contrast sensitivity Because of these unpleasant drawbacks, manysurgeons went back to implanting conventional monofocal IOLs The results of recentmultifocal IOLs are more promising and the interest in this type of IOL has increasedagain

Before describing theoretical benefits and caveats, one should understand the differentdesigns of IOL

1 Different Types of Multifocal IOLs

b Diffractive Type

Another type is the diffractive type, which is not affected by pupil size This IOL has a0.6-mm central zone and some 30 annular diffracting zones on its posterior surface (Fig.1E) The light can be diffracted toward two foci; 41% for near and 41% for distance.Thus, 18% of the light would be lost, and the loss of contrast sensitivity became thebiggest concern

2 Theoretical Benefit

a Less Dependence on Spectacles

Theoretical benefits of multifocal IOLs are based on their depth of focus Figure 2 showsthe results of distance visual acuity with defocus of the patient from emmetropia followingAMO ARRAY There are two spikes, which means that the patient can focus both farand near Another interesting thing about this particular IOL is that the valley betweentwo spikes is not deep and patients have a chance to see things at middle distance Thus,the potential of not depending on spectacles is high

3 Theoretical Caveat

a Decreased Contrast Sensitivity

The caveat of multifocal IOLs in general is the loss of contrast sensitivity due to theirdesign By in a randomized study of multifocal IOLs, a significant decrease of visualacuity was reported at 11% contrast with multifocal IOLs compared to the monofocalIOLs (1) Although this problem can be detected by examination of contrast visual acuity,most patients do not have the problem in daily life

239 Multifocal IOLs for Presbyopia

Figure 1 (A) IOLAB two-zone refractive type with a central 2-mm button for near (B) IOPTEX.(C) Pharmacia (D) AMO ARRAY (E) Diffractive IOL (3M) This IOL has a 0.6-mm central zoneand some 30 annular diffracting zones on its back surface

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Figure 2 Defocus curve Two spikes for far and near can be observed

b Glare and Halo

Another caveat would be glare and halo, especially at night When the pupil is dilated indim light, some patients recognize halo due to its annular design

c Incorrect Power

The correct biometry is very important for this particular IOL Especially when clear lensextraction is planned, this is critical Patients expect better uncorrected vision at far andnear Even with perfect surgery, the results can be miserable if the IOL power calculationfails

Some indications and contraindications depend on the type of multifocal IOL Recentrefractive-type IOLs are indicated for most patients if they are not included in exclusioncriteria (Table 1)

1 Cataract

In case of cataract surgery for a younger patient, this IOL can avoid the loss of tion, an undesirable complication The results in this age group may represent the possibil-ity of treating presbyopia

accommoda-241 Multifocal IOLs for Presbyopia

Table 1 Exclusion Criteria

Patient with multifocal IOL in the fellow eye

Uncontrolled glaucoma

Progressive diabetic retinopathy

Corneal lesions that may affect visual acuity

Other complications that may affect visual acuity

Preoperative astigmatism greater than 1.5 D

Frequent driving or operation of dangerous machinery at night

2 Expectation of the Patient

The patient who is highly motivated is often a good candidate The increased number ofrefractive surgeries has proved that many patients long for life without spectacles andcontact lenses Younger patients underage 45 are also candidates, since the most undesira-ble complication following cataract surgery at this age is the loss of accommodation.Despite their perfect vision at far, they may suffer from the new experience of not beingable to read without spectacles

3 Occupation

Individuals with occupations that require good far and near vision in which the use ofspectacles or contact lenses might be dangerous represent another good candidate group

The preferred surgical techniques should provide predictability of postoperative refractionand stability of IOL position For this purpose, small incision and continuous curvilinearcapsulorhexis (CCC) are recommended

1 Incision

It is well known that surgically induced astigmatism has recently been diminished by theuse of small-incision cataract surgery For this purpose, a foldable multifocal IOL ispreferable Also, a self-sealing incision should be made so as to avoid suture-inducedastigmatisms

phenom-3 Posterior CCC

Near vision can easily be decreased by the posterior capsular opacity with multifocal IOLs

In other words, the rate of neodymium:YAG capsulotomy is higher than that of monofocal

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Table 2 Visual Acuities with Different Multifocal IOLs

Lindstrom Usui and Negishi and(1993) associates (1992) associates (1997)IOL

20/40 or better94.9%

a neodymium:YAG capsulotomy may be necessary earlier

a Clinical Results

There have been many reports on the results of multifocal IOLs following cataract tion The reports on multifocal IOL with clear lensectomy are limited The desirable resultswith cataract patients persuade clear lensectomy for the patient who would like to haverefractive surgery, including the correction of presbyopia

extrac-b Visual Acuity (VA)

Table 2 shows the reported results of several multifocal IOLs (2) The time-lapse changes

of the mean postoperative VA in a Japanese clinical study are shown in Table 3 Theaverage distance uncorrected VA was 20/25, best corrected VA was better than 20/20.For near, uncorrected VA was 0.39, with distance correction, it was 0.43; and best corrected

Table 3 Time Lapse Changes of the Average VA

ObservationPre-op 1 day 1 week 1 month 3 months 6 months 1 yearUncorrected distance VA 0.13 0.63 0.73 0.74 0.69 0.73 0.78Corrected distance VA 0.23 0.90 1.06 1.08 1.07 1.05 1.12Uncorrected near VA 0.13 0.29 0.34 0.36 0.40 0.41 0.39Distance-corrected near VA 0.13 0.30 0.36 0.38 0.39 0.40 0.43Best corrected near VA 0.20 0.56 0.74 0.73 0.72 0.72 0.77

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VA was 0.77 The VA at the 1 week postoperative visit was as good as the one at 1 year

We can expect early visual recovery with this type of IOL

d Halo and Glare

Halo and glare are also of concern following multifocal IOL surgery One year after theoperation, patients were asked about halo and confirmed its intensity At each final follow-

up observation, 22.4% complained mild or moderate halo, which was only a transientsymptom in every case against sun in daytime and/or light sources at night This was notexperienced to the extent of causing problems in daily life Glare values were measured

by Miller-Nadler Glaretester and percent glare was 5.6 No percent glare decrease wasobserved, potentially generating clinical problems

e Spectacle Usage

It is not easy to analyze spectacle usage, since some patients use spectacles most of thetime and the others use them only when necessary Approximately 60% were able tofunction comfortably without spectacles Figure 5 shows the changes of using spectacles

by the follow-up time Until 1 month after operation, most patients were not using

specta-Figure 3 Contrast sensitivity The mean contrast sensitivity after the operation was above thelowest of normal range

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Figure 4 Contrast visual acuity Contrast VA of the eye with multifocal IOL (array) in 15 and2.5% contrast was comparable to that with monofocal IOL

Figure 5 Changes of using spectacles

Figure 6 Patient’s satisfaction