Atti del convegno
European Contact Lens Society of Ophtalmologists ECLSO 2003
18-21 Settembre 2003 – Venezia Italia
Abstract del congresso inerenti l’ortocheratologia.
Halons and ghost images during orthokeratology treatment:
Problem Solving. POSTER Giuseppe Toffoli – Padua – Italy Riccardo Olent – Turin - Italy
Introduction.
The improvement of the orthokeratology techniques, the aid of instruments
for the control of the corneal shape and the use of software for the calculation
and design of contact lenses have allowed the practioner to relate the geometric
parameters of contact lenses with the corneal shape modification. Purpose.The
aim of present study is to solve the problem of halons and ghost images
perception during orthokeratology treatment in myopic subjects.Material
and Methods. In four young adult subjects night wearing reverse-geometry
rigid gas-permeable lenses (custum design fit), corneal topographic changes
were monitored (15, 30 60, 90 days after start wearing) using the Optikon
Scout corneal topographer. The treatment zone diameter, induced by thecontact
lenses, was measured and compared with scotopic pupilaperture. Subjects
reported in each topographic session if overnight they perceived halons
and gosht images. In subjects in which this problem persisted after 60 days,
the contact lenses were changed by enlarging the optic zone dimension. Results.
All thesubjects perceived halons after 15 days of treatment. Only 2 subjects
had the problem after 30 days and1 subject still after 60 days. This subject,
after 30 days from the change of the contact lenses, solves the problem
of halons.Conclusion. Although this work need more confirm, the corneal
treatment zone dimension is proportional to contact lenses’s optical
zone and the problem of halons and gosht image could be present if it’s
smaller then scotopic pupill’s aperture.
Key Words: orthokeratology, corneal molding, halons, ghost image, optical
zone.
Microstructural corneal changes in orthokera tology Gudrun Bischoff Hamburg, Gennany
Orthokeratology is a method, which modifies the structure of the anterior
corneal tissues. The older techniques and lens types darnaged and folded
the stromal collagen-larnellae. The question was, if the new technique and
lens design is less stress-inducing and if possible changes are restricted
to the epithelial celllayer, as the advertisement makes us believe. The
cellular structures were pictured by a confocal microscope. Investigated
were OK-wearers of different contactological history and time of wearing
OK-lenses. The result could not be covered under one headline. The spectrum
of results carne from no measurable changes to massive microcysts. Referring
to age of patient and type of earlier worn lenses the changes to be found
were predictable. Typical distortion of the collagen-lamellae was not detected.
So far the new method is more acceptable than the earlier type of OK-lenses,
fitted 15 years ago
Empirical advanced orthokeratology through corneal
topography: the university of houston clinical study Sami El Hage, Nonnan Leach, William Miller, Katrina Parker, and Amber
Gaume Eye Care Associates, Houston, Texas, U.S.A.
Introduction. There is increasing evidence
that reverse geometry rigid gas permeable (RGP) contact lenses when woro
at night will flatten central coroeal curvature resulting in improved unaided
visual acuity in low to moderate myopes. Traditionally, these designs have
characteristically required the use of diagnostic lenses to determine the
best fit for a given wearer. Objective: The purpose of this study is to
colIect scientific and cIinical data on twenty-five subjects and to determine
the validity of fitting advanced accelerated orthokeratology lenses (CKR)
empirically from coroeal topography without the use of diagnostic lenses.
Method: Seventeen subjects, 18-37 years of age having naturally occurring
myopia of between1.00 D. and -4.00 D. with astigmatism no greater than -1.50
D. who signed the informed consent document were entered into this six-months
study. Coroeal topography, Confocal microscopy, ultrasound coroeal thickness,
aberrometry, and slit-Iamp biomicroscopy were used to assess changes occurring
in the coroea. Unaided logMAR visual acuity, subjective refraction, and
a questionnaire were used to monitor vision and subjective symptoms. FolIow-up
visits are scheduled at one day, one week, two weeks, one month, three months
and six months. Results: To date seven subjects have completed their l-month
visit. Unaided acuity improved from 0.89:tO.22 OD/0.74:tO.30 OS to 0.03:1:.12
OD/O.Ol:1:.13 OS. Myopia was decreased from -2.61 D.:tO.85 OD/-2.07 D.:tO.29
OS to +0.07 D.:tO.40 OD/Plano:tO.32 OS. Shape factor as deterrnined by coroeal
topography increased from 0.83:1:0.13 OD/0.82:tO.07 OS to 1.26:tO.24 OD/1.32:tO.31
OS indicating a shift from a prolate to oblate coroeal surface. Total central
coroeal thickness as determined by Orbscan pachymetry was 555.57:1:49.89
mm OD/551.57:1:46.88 mm OS at baseline and 548.71:1:43.61 mm OD/547.00:l:47.23
mm OS at l-month. Total central coroeal thickness as deterrnined by Sonogage
ultrasonic pachymetry was 549.71:1:37.88 mm OD/546.43:1:44.11 mm OS at baseline
and 561.75:1:44.68 rnm OD/565.50:1:47.22 mm OS at l-rnonth. Total central
coroeal thickness as determined by confocal microscopy was 517.52:1:69.15
rnm OD/474.15:1:65.69 mm OS at baseline and 502.17:1:86.82 mm OD/544.00:I:48.23
mm OS at l-month. Central coroeal epithelial thickness measured with the
Sonogage was 46.7I:tO.76 mm OD/46.86:tO.38 mm OS at baseline and 47.25:1:1.26
rnm OD/47.25:tO.50 mm OS at l-month. Central coroeal epithelial thickness
measured with confocal microscopy was 50.72:1:17.61 mm OD/44.85:1:7.03 mm
OS at baseline and 53.53:1:9.13 mm OD/31.96:1:17.92 mm OS at 1month. Discussion:
The amount of myopia reduction found at the l-week visit was clinically
insignificant from the I-month results indicating that the fulI effect is
achieved by one week. However, neither total nor epithelial coroeal thickness
measurements show any significant changes from baseline regardless of the
method used. Central and inferior coroeal sensitivity measurements also
showed no significant changes. These preliminary results demonstrate the
effectiveness of the CKR lens design at reducing myopia and improving unaided
visual acuity.
Models of posterior corneal change with overnight
orthokeratology Helen Owens*, Leon Gamer*, Greg Gamble**. *Department of Optometry &
Vision Science, University of Auckland, AuckIand, New Zealand. ** Department
of Medicine, University of AuckIand, AuckIand, New Zealand.
Background. The mechanism relating refractive
change to coroeal tissue changes foIlowing overoight orthokeratology remains
uncertain, particularly with regard to the contribution fcom the posterior
coroeal surface. The aim of this work was to assess topographical changes
in the posterior coroeal surface following one month of overnight orthokeratology
lens wear and to model those changes in relation to coroeal oedema and moulding.
Metbods Coroeal topography, subjective refraction, ultrasound coroea1 thickness
and Purkinje imaging techniques were used to assess changes occurring in
the coroea for 20 subjects over a course of one month, at four separate
time periods. Biometric measurements concentrated on areas in the central
2.5mm and mid-peripheral 5mm of the coroea. Results Orthokeratology successfuIly
reduced subjects' myopia in an exponential manner over the course of a month.
The reduction in myopia was accompanied by flattening of anterior and posterior
coroeal surfaces, both centrally and mid-peripheralIy. Changes from baseline
were significant at all times for the anterior coroea and significant over
the initial 2 weeks for the posterior surface. Conclusions Qur results demonstrate
that the coroea bends during the initial 2 weeks of overoight lens wear.
Models of the central coroea suggest that a combination of oedema and moulding
is likely to account for these posterior coroeal changes.
Orthokeratology with overnight wear reverse.geometry
contact lenses in practice Dr. A J P Rouwen, MD, PhD S. de Graaf, Opt, Orthop. Central Military
& University Hospital, Refractive Surgical Centre, Utrecht, The Netherlands
The goal of this presentation is to make the delegates familiar with
the fitting process of these lenses in practice, to elaborate the limitations
of the results attainable with these lenses and aIso to show methods to
judge the final optical results of these lenses. Reverse geometry OK lenses
work by virtue of the eccentricity value of the corneal shape. Correction
of low-grade myopia with limited correction of comeal astigmatism depends
on the actual eccentricity value of the coroea. The amount of correctable
myopia can be calcuIated fram the measured corneal shape. Low grade, not
completely stable rnyopia in young patients is a good indication for this
technique as compared to refractive surgery. Together with refractive surgery
this technique is a method to have 20/20 V A during the day without spectacle
or contact lens wear.
The fitting procedure is completely different from normal RGP fitting as
is the judgement of fluorescein fitting pattems. Calculation is made more
easy, because we used a computer program made by NKL, the laboratory also
manufacturing these BE MountfordINoack Australian design lenses. The topographic
response after the first night sleep in the triallenses is used to find
the correct lens to order for successive wear. The correct assessment of
these topographic (difference) plots after overnight triallens wear is essential
to get good results with this OK technique. On the basis of this response
the calculating program often advises to refit with another triallens in
order to get the proper first night result and to find the definite recipe
lens. The correct power in the finallenses is only used during the (early)
night when the patients want to see more with large pupils or fading effect
from lens wear the night before. On the other hand some patients are able
to skip lens wear every other night, while keeping their correction. Limitations
in both refractive effect and topographical changes are shown on the basis
of three actual fittings done in our clinic. AdditionalIy some common adverse
effects are shown.
Results of the first clinical study in france on overnight
orthokeratology Dr. Adrien SARFATI Hopital Hotel-Dieu, Paris, France Claude HATCHUEL,
Aix-en-Provence, France
In this clinical study we investigated the performance of modern, overnight
Orthokeratology using RGP lenses with reverse geometry design and high oxygen
permeability. The patient group included persons of varied ages, and myopia
of -1.00 D to-3.50 D. We tested the clinical and optical efficacy of the
procedure and the limits of reducing myopia by ovemight wear of the Ortho
K lenses over a penod of three months. All patients were regularly controlled
for corneal complications. We determined the optimal fitting procedures
and evaluated which patients would be eligible for overnight Orthokeratology
. Initial results confirm earlier studies: We obtained good results and
good safety on patients with low myopia.
Is ortho-k - ok? Eef van der Worp Prívate Ophthalmology Clinic, Amsterdam, The
Netherlands
Orthokeratology has recently gained renewed attention in the interoationalliterature
and on conferences around the world. Reasons for the spectacular comeback
of this mode of lens wear are primarily the development of new technology
(coroeal topography and better lens designs), new insights in the mechanisms
oí coroeal reshaping, and the possibility of overnight wear. lt is
our task to evaluate whether this modified technique of orthokeratology
is an acceptable mode of vision correction. Is Ortho-K OK?
The mechanism behind orthokeratology is still unclear. Central coroeal thinning
is reported in a number of occasions and is presumed to cause the refractive
change. The central coroeal thinning appears to be epithelial in origino
Compression of epithelial cells, redistribution of epithelial cells or both
might cause the effect. In the mid-periphery of the coroea, an increase
in coroeal thickness has been noted. According to the leading investigators
in this field, this change is presumably stromal. Refractive change usually
is restricted 10 low myopia, refractive error change of 2.25D +/- 1.00D
is COIWllon. Unaided visual acuity of 20/20 in the morning is possible and
is reported in most (74%) successful cases. Higher myopia will typically
reduce the optical treatrnent zone and may result in visual compromise.
Some lens designs seem better in treating higher myopia than others. Ortho-k
is approved by the US Food and Drug Administration for up to -6.00D. Hyperopic
and presbyopic corrections are in development, but not available at this
stage.
The preferred method for myopia reduction for the vast majority of researchers
and practitioners is overoight Ortho-k. Oxygenation of the coroea and the
risk of bacterial epithelial binding is therefore an issue and will be discussed
in this presentation. There are case reports in the interoational literature
reporting coroeal infectious ulcers, predominantly Pseudomonas aeruginosa,
resulting in a loss of best corrected visual acuity after recovery in some
cases. Most cases reported are from Asian countries, especially China.
Another potential risk in overoight Ortho-k is lens adherence, especially
upon awakening. Tear film composition plays a vital role in this and tear
supplements in the moroing are usually recommended. Some leos designs have
the tendency to create more lens adherence than others. In addition, coroeal
rings have been observed in some patients after wearing Ortho-k lenses.
These rings are unknown in origin and similar rings have been found in post-PRK
and post LASIK patients as well. The location of the coroeal iron rings
in Ortho-k coincided with the fitting curve of the reverse-geometry rigid
contact lens, suggesting that the rings might have developed from tear pooling.
Morphological changes of rabbit cornea by orthokeratologylens Masao Matsubara and Yasuo Ishii
Dept. of Ophthalmology Tokyo Women's Medical University, Daini Hospital
& New Vision Institute, Japan
PUlpose: To investigate the histopathological
and physiological changes of coroea after the use of orthokeratology lens.
Methods: Orthokeratology lens (OK lens) (BE,
Dreim or Contex. Targeted reduction; 3 or 6 D) was placed on right eyes
of white rabbits for 7 hours daily. Eyes were enucleated after 1, 4 and
12 weeks, and served to light or electron microscopic study. Left eyes were
used as controls. Eyes with OK lens (Euclid) for 2 or 3 weeks were served
to histochemical study.
Results: With successful topographical reduction
in refraction, epithelial layer was histologically stable after any periods
of the schedule. Epithelial cells showed normal configuration at the center
of the coroea. Histochemical staining suggested almost normal function of
epitheliallayer. Electron microscopic study revealed higher electron density
in epithelial cells than in those of control. Glycogen granules in epithelial
ceU cytoplasm and proteoglycans in deep stroma slightIy increased at the
center. No other apparent abnormal findings were observed.
Conclusions: Orthokeratology lens gave topographical
change with very mild functional and morphological changes in rabbit coroea.
A new customized esa.curve reverse geometry lens design
for overnight orthokeratology Antonio Calossi Firenze, Italy
We developed and patented a new design and calculation method to custornize
a multicurve reverse geometry lens. This new design is based on a biconic
model on which we developed an esa-curve custornize reverse geometry lens
designo We present the results of a pilot study to evaluate the success
and safety of treatment with these ovemight orthokeratology contact lenses.
Refractive error, comeal topography, and biomicroscopic data were collected
to determine the amount of refractive error change achieved, corneal changes,
and a safety profile of overnight wear of these lenses for overnight orthokeratology.
In this pilot study we treated 30 eye of 15 patients aged from 18 to 43
years, without any tear, comeal, ocular andlor systemic disease at the
baseline time and without any previous ocular surgery. The baseline refractive
error was from -1.00 to4.00 D spherical equivalent, WTR astigmatism up
to 1.50 D and ATR or oblique astigmatism up to 0.75 D. The preliminary
results of our pilot study indicate that the cornea responds rapidly to
the application of these custornize esa-curve reverse geometry lenses,
with significant central comeal flattening and improvement in visual acuity
after just 60 min of lens wear; the comeal shape change from prolate to
oblate asphericity after 1 night of wear; improvement in unaided visual
acuity up to 20/20 can be obtained for at least 10 h after lens removal
in an average time of 10 nights. Qur data suggest that the comeal epithelium
is able to be molded or redistributed very rapidly in response to the
tear ftlm forces generated behind this reverse-geometry lenses designo
Up to 1 year of overnigbt wear, safety and efficacy of the procedure appear
to be favorable; however, future studies are needed to determine the more
long-term outcomes of treatment.
Orthokeratology: A
Retrospective Study Paige N. , Mustaler L.
Abstract:
The Ortho-k data of seventy five patients fit over different time spans
were examined. All patients were fit with the PLI system that involves fitting
the patient with the first lens 1.00 D. flat until maximal reduction in
"K's" has occurred. The second lenses are generally fit another diopter
flatter than the new "K' reading. The mean reduction in myopia was 1.74
diopters initially but fell to an average of 1.41 diopters over two years.
Age was not a factor in success nor was the fact that the patient had worn
either soft or rigid lenses prior to Ortho-K treatment. The low range myope
(-1.75 or less) should be expected to achieve emmetropia and 20/20 acuity.
The author noted that not one person "advanced further into myopia than
the amount present before treatment, and it appears that Ortho-k exhibits
an inhibitory control over the myopic advances normally expected".
