In as omal Co neal Ring Segmen in
Mode a e o Se e e Ke a oconus: Re ac i e,
Topog aphic and Abe ome ic Changes
Ja ie González-Pé ez1*, Jacobo Ga cía Quei uga1, Rosa io Tou iño Pe alba2,
Lau a Ma ínez-Pé ez2 and Mª Te esa Rod íguez A es2,3
1Depa men o Applied Physics (Op ome y), Uni e si y o San iago de Compos ela, Spain
2Oph halmology Se ice, Uni e si y Hospi al Complex o San iago de Compos ela, Spain
3Depa men o Su ge y (Oph halmology), Uni e si y o San iago de Compos ela, Spain
In oduc ion
Ke a oconus (KC) is a common, p og essi e co neal disease esul ing in ch onic hinning
and p o usion o he pa a-cen al co nea associa ed wi h myopia, i egula as igma ism
and high o de abe a ion inc ease [1]. The ea men di e s depending on he s age o he
diso de . Visual acui y can be imp o ed wi h spec acles in he ea ly s age o his condi ion
o wea ing con ac lenses also e ec i e o p o ide a good ision in mode a e KC [2]. When
an op ical co ec ion is no longe e ec i e, o no con ac lenses a e well ole a ed, se e al
su gical ea men s a e used o he ea men o KC, including In aco neal Co neal Ring
Segmen s (ICRS) and co neal collagen c oss-linking (CXL) [3,4]. Howe e , KC may e en ually
equi e co neal g a ing as hei se e e condi ion p og esses, ep esen ing he mos common
indica ion o ke a oplas y in he de eloped wo ld [4]. Nowadays, he e is a g owing in e es
in ea men op ions ha may delay o de e co neal g a ing, including ICRS implan a ion,
o iginally used o co ec mode a e- o-se e e myopia, by exe ion o a e-modelling e ec
C imson Publishe s
Wings o he Resea ch Resea ch A icle
*Co esponding au ho : Ja ie González-
Pé ez, Depa men o Applied Physics
(Op ome y), Uni e si y o San iago de
Compos ela, Spain
Submission: No embe 11, 2023
Published: Janua y 29, 2024
Volume 3 - Issue 3
How o ci e his a icle: Ja ie González-
Pé ez*, Jacobo Ga cía Quei uga, Rosa io
Tou iño Pe alba, Lau a Ma ínez-
Pé ez and Mª Te esa Rod íguez A es.
In as omal Co neal Ring Segmen
in Mode a e o Se e e Ke a oconus:
Re ac i e, Topog aphic and Abe ome ic
Changes. Med Su g Oph hal Res. 3(3).
MSOR. 000565. 2024.
DOI: 10.31031/MSOR.2024.03.000565
Copy igh @ Ja ie González-Pé ez, This
a icle is dis ibu ed unde he e ms o
he C ea i e Commons A ibu ion 4.0
In e na ional License, which pe mi s
un es ic ed use and edis ibu ion
p o ided ha he o iginal au ho and
sou ce a e c edi ed.
ISSN : 2578-0360
1
Medical & Su gical Oph halmology Resea ch
Abs ac
Aim: This s udy e alua es he opog aphic and abe ome ic changes induced by ICRS in pa ien s wi h
mode a e and se e e ke a oconus and analyzes p e-ope a i e ac o s a ec ing he e ac i e and isual
ou comes.
Me hods: This e ospec i e, obse a ional, non andomized, and single-cen e case se ies, included
21 ke a oconic eyes o 21 pa ien s implan ed wi h Ke a ing ICRS (Mediphacos, Belo Ho izon e, B azil),
using he manual unneliza ion echnique and acuum de ice. All subjec s we e examined a e 6 mon hs
ollowing su ge y, including he measu emen o unco ec ed isual acui y (UCVA), bes -Co ec ed
Dis ance Visual Acui y (CDVA), e ac i e da a, pachyme y, co neal opog aphy, and abe ome y.
Resul s: The mean age o 21 pa ien s was 31.14±10.65 yea s, ele en (52%) we e male. Ke a ings we e
success ully implan ed in all eyes. A e 6-mon h om implan a ion, signi ican inc ease was ound in
mean UCVA (P<0.01) and CDVA (P<0.01). The e was a s a is ically signi ican educ ion in e ac i e
cylinde (P<0.01), co neal cylinde (P=0.020), Kmax (P<0.01) and BFS (P=0.02). S a is ically signi ican
di e ences we e ound in se e al abe ome ic pa ame e s o 6-mm pupil, RMS HOA (P=0.045), oblique
as igma ism (P=0.009), e ical coma (P=0.02), and oblique e oil (P=0.018).
Conclusion: Analysis o he isual ou comes a e Ke a ing ICRS implan a ion showed a signi ican
pos ope a i e co neal la ening wi h a subsequen inc ease in UCVA and CDVA. Visual, e ac i e,
opog aphic and abe ome ic pa ame e s ema kably change in he 6-mon h pe iod a e Ke a ings
implan a ion. Ke a ings in his sample ha e shown o p o ide a mild isual ehabili a ion be ween 2 and
3 lines, pa icula ly in mo e ad anced cases. Fu he mo e, la ening o he an e io segmen induced by
he su ge y migh be bene icial o con ac lens i ing.
Keywo ds: Ke a oconus; In as omal co neal ing segmen s; Ke a ing; Vacuum sys em; K as igma ism;
Sphe ical abe a ion; Coma; Co neal hickness
2
Med Su g Oph hal Res
Copy igh © Ja ie González-Pé ez
MSOR.000565. 3(3).2024
on he co neal s oma [5-7]. The implan a ion means he addi ion
o ex a ma e ial a he mid-pe iphe al co nea and subsequen ly
educing s eepening o he cen al a ea. This e-modelling is
in ended o dec ease e ac i e e o magni ude, imp o e cen al
co neal su ace egula i y and, mo eo e , o inc ease co neal
s abili y and delay he p og ession o KC [8]. I has been epo ed
ha changes in he co neal s oma induced by ICRS a e di ec ly
p opo ional o he hickness and in e sely p opo ional o i s
diame e and dep h o implan a ion [9,10].
The e a e se e al comme cially a ailable ICRS ha di e in
hei sec ion shape, diame e , a c leng h, hickness, and zone o
implan a ion. The Ke a ing ICRS (Mediphacos, Belo Ho izon e,
B azil), is a small, a c-like segmen made o polyme hyl me hac yla e
cha ac e ized by a 5 o 6mm diame e and unique p isma ic
design a ailable in di e en a c leng hs (90º, 120º,160º,210º and
355º), wi h a iable hickness anging om 150 o 350mm (in
50mm inc emen s). In he las 10 yea s, se e al clinical s udies
ha e a emp ed o demons a e hei e icacy o imp o e isual
unc ion, educing he magni ude o co neal as igma ism, and
la ening he cen al co nea [11-14]. I has been p oposed ha he
p eope a i e mani es e ac ion o bes co ec ed isual acui y a e
p edic i e ac o s wi h a limi ed abili y o p edic he pos ope a i e
isual ou come, while abe ome y has been ound o ha e a
be e p edic i e po en ial [15]. The assessmen o isual and
mo phological ea u es should p o ide aluable insigh s in o he
de e minan s o he co ela ion be ween co neal su ace p ope ies
and he imp o emen o isual acui y ollowing ICRS su ge y.
Al hough his subjec has al eady been s udied, he e is s ill a lack
o publica ions conce ning he mo phome ic and isual ou comes
a e Ke a ing ICRS implan a ion using he manual echnique,
especially in he ecen pe iod. Despi e new app oaches using
he inc easingly equen em osecond echniques, hose a e no
a ailable o many su geons a ound he wo ld. In addi ion, he e
is s ill a lack o in o ma ion conce ning he ou comes on se e e
ke a oconus pa ien s. The aim o his s udy was o con ibu e
o de e mine how ICRS su ge y a ec o mo phome ic co neal
pa ame e s and iden i y ac o s a ec ing he opog aphic and
isual ou comes ollowing Ke a ing ICRS implan a ion in a no h-
wes o Spain sample.
Subjec s and Me hods
To e alua e he impac and implica ions o ICRS implan a ion
on he co neal su ace, we conduc ed a e ospec i e, obse a ional,
non andomized, and single-cen e case se ies o pa ien s implan ed
wi h Ke a ing segmen s (Mediphacos, Belo Ho izon e, B azil) using
he manual echnique.
Sample and inclusion c i e ia
The s udy was conduc ed a he An e io Segmen Uni
om Hospi al de Conxo-Complejo Hospi ala io de San iago
de Compos ela (A Co uña, Spain), and comp ises a o al o 21
mode a e and se e e KC subjec s acco ding o he Amsle -K umeich
classi ica ion, aged 31.14±10.65 yea s. The s udy p o ocol was
app o ed by he E hic and Scien i ic Commi ees o he Uni e si y
o San iago de Compos ela (Spain) and ollowed he ene s o he
Decla a ion o Helsinki. Eligibili y c i e ia included KC subjec s, 18
yea s o age o olde , showing educed spec acle/con ac lens bes
co ec ed dis ance isual acui y o con ac lens in ole ance and
maximum co neal powe (Kmax) be ween 49 o 70 D. Diagnosis
and g ading o he disease was based on co neal opog aphy and
sli lamp examina ion.
Ocula assessmen
All pa ien s unde wen a comple e p eope a i e examina ion,
including ou ine e alua ion o Snellen Unco ec ed Dis ance
Visual Acui y (UDVA), Snellen Bes -Co ec ed Dis ance Visual
Acui y (CDVA), e ac i e e o , undus examina ion, sli lamp
biomic oscopy, co neal opog aphy and pachime y wi h pa icula
a en ion o he occu ence o ocula ad e se e en s. Topog aphic
analysis was pe o med using Pen acam (Oculus GmbH, We zla ,
Ge many), which include 3mm-a ea ke a ome ic eadings, co neal
as igma ism, kmax, eccen ici y, co neal hickness (minimum,
apex and cen al), and se e al abe ome ic pa ame e s. The
same p o ocol was applied p eope a i e and 6-mon hs a e ICRS
implan a ion.
Su ge y and pos ope a i e p ocedu es
All su ge ies we e pe o med by he same su geon unde
s e ile condi ions wi h opical anes hesia 0.5% p opa acaine
hyd ochlo ide solu ion (Alcaine, Alcon). The app op ia e
Ke a ing segmen s diame e (6-mm diame e ), hickness and
leng h (deg ees) we e selec ed in acco dance wi h nomog am
p oposed by he manu ac u es, and hen implan ed in o he eye.
The incisions we e always made in he s eepes co neal me idian.
Co neal unneliza ion o ing segmen inse ion was pe o med
by mechanical echnique dissec ion and a Ke a ing acuum de ice
(Mediphacos, Belo Ho izon e, B azil) was employed o s abilize he
globe and o keep he plane o dissec ion o he unnel by suc ion.
A e ma king he geome ical cen e o he co nea, a 1.2mm adial
incision was pe o med using a calib a ed diamond blade (Sinskey
hook), a he dep h o 80% co neal hickness a he s eepes
me idian. An in as omal pocke was c ea ed using a small incision
wi h a semici cula mic o-dissec o ha ope a es unde suc ion,
un il inishing he unnels in he desi ed di ec ions (clockwise and
coun e clockwise dissec ion) and 6mm in diame e . Once his s ep
was comple ed, he su geon emo es he suc ion and he Ke a ing
implan was placed in o he pocke using implan a ion o ceps. The
pocke was sel -sealing and did no equi e su u ing. Subsequen ly,
a Pu eVision silicone hyd ogel bandage con ac lens (Bausch &
Lomb) was placed on he co nea and hen emo ed 1 day a e he
su ge y. No in aope a i e complica ions occu ed. Pos ope a i e
ea men comp ised be ame hasone d ops ou imes a day, opical
ob amycin 0.3% (Tob ex, Alcon) ou imes a day, and p ese a i e-
ee a i icial ea s (A elac Rebalance, Bausch & Lomb, Inc., No h
B idgewa e , NJ, USA) six imes a day. The ob amycin d ops we e
discon inued 1 week a e he su ge y, while he be ame hasone
dosage was ape ed o e a pe iod o 4 o 6 weeks.
Da a Analysis
The Shapi o-Wilk no mali y es was implemen ed o assess all
da a se s o no mal dis ibu ion. The ca ego ical a iables (sex and
3
Med Su g Oph hal Res
Copy igh © Ja ie González-Pé ez
MSOR.000565. 3(3).2024
numbe o igh and le eyes) a e exp essed as equencies. The
con inuous a iables (age and he p e- and pos ope a i e UDVA,
CDVA, sphe e, cylinde , sphe ical equi alen , K1, K2, Kmean, Kmax,
co neal pachome y and abe ome ic measu emen s) a e exp essed
as means wi h S anda d De ia ions (SD) o easie compa isons and
in e p e a ion wi h he exis ing li e a u e. The di e ences be ween
he p eope a i e and pos ope a i e measu emen s we e compa ed
using pai ed - es s when pa ame ic s a is ical analysis was
possible, and he Wilcoxon Signed anks es o non-pa ame ic
e alua ion. Pea son o Spea man co ela ion coe icien s we e used
o e alua e co ela ion be ween di e en a iables, depending on
whe he no mal dis ibu ions o da a we e obse ed. Fo s a is ical
pu poses, P alue less han 0.05 was conside ed s a is ically
signi ican . SPSS .24.0.0.0 (IBM Co po a ion, A monk NY) and
Excel .15.0 (Mic oso Co po a ion, Redmond WA) so wa e we e
used o all s a is ical analysis and g aphs.
Resul s
Visual and e ac i e pa ame e s
A summa y o he isual and e ac i e changes in eyes
implan ed wi h ke a ing segmen s a e shown in Table 1. Bo h, mean
UDVA and CDVA we e signi ican ly inc eased ollowing 6-mon hs
a e ICRS implan a ion. Mean p eope a i e sphe e, co neal cylinde
and mani es sphe ical equi alen we e signi ican ly dec eased
a 6-mon hs a e su ge y. Howe e , when ec o decomposi ion
o e ac ion was pe o med J0 and J45 ec o s changes we e no
s a is ically signi ican .
Table 1: Re ac i e changes da a be o e and 6-mon hs a e su ge y.
UDVA (unco ec ed dis ance isual acui y); CDVA (co ec ed dis ance isual acui y); MRSE (mani es e ac i e sphe ical equi alen );
J0 (Humph ey ec o c oss cylinde compound ixed a 0º/90º); J45 (Humph ey ec o c oss cylinde compound ixed a 45º/135º); D
(diop e)
aPai ed samples - es ; bWilcoxon signed ank es
Va iable P eope a i e Pos ope a i e Change P
UDVA (Snellen) 0.12±0.15 0.35±0.19 0.23±0.09 <0.001b
CDVA (Snellen) 0.47±0.21 0.68±0.17 0.21±0.18 0.005a
Sphe e (D) -3.43±2.21 -2.27±2.55 1.16±2.36 0.023b
Cylinde (D) -5.42±1.94 -2.08±1.48 3.33±1.53 0.002a
MRSE (D) -5.14±2.69 -3.32±2.50 1.82±2.58 0.004a
J0 (D) 0.18±1.97 -0.07±1.07 -0.24±2.01 0.584a
J45 (D) -0.02±2.17 -0.10±0.73 -0.08±2.05 0.867a
Topog aphic pa ame e s and pos ope a i e ou comes
Table 2 summa izes opog aphic and pachome ic da a
p eope a i e and 6-mon hs a e Ke a ings implan a ion. As shown
in Figu e 1, he Ke a ings la ening e ec was mo e e iden in
he s eepes 3-mm a ea (P=0.05) when compa ed wi h he mean
3-mm ke a ome y eadings wi h a 1.94 D dec ease e ec on he
an e io co neal as igma ism (P<0.001). The s onge la ening
e ec was obse ed on he maximum ke a ome y eadings when
compa ed p e- and pos ope a i e alues (P<0.001). A simila
end was obse ed in he adius o an e io Bes Fi Sphe e
(BFS) p eope a i e and 6-mon h a e su ge y (P=0.020). Mean
Cen al Co neal Thickness (CCT) showed a sligh ly highe inc ease
(2.0%), al hough non-clinically signi ican a e 6-mon hs o ICRS
implan . A simila end was obse ed o apex (P=0.186) and
minimum co neal hickness (P=0.067). As expec ed, signi ican
co ela ions we e ound be ween pos ope a i e ou comes and
p eope a i e opog aphic co neal pa ame e s, as well as segmen
pa ame e s (Table 3). Using he nomog ams o ICRS implan a ion
ecommended by he manu ac u e, we ound a mode a e
co ela ion be ween he hicke Ke a ing segmen s and changes in
mani es cylinde ( =0.491; P=0.023) and changes in BFS ( =0.440;
P=0.046).
Table 2: Summa y o he opog aphic and pachome ic da a a e 6-mon hs Ke a ing implan a ion.
K1 (co neal powe in he la es 3-mm a ea); K2 (co neal powe in he s eepes 3-mm a ea); k2-k1 (mean co neal
as igma ism in he 3-mm a ea); Km (mean co neal powe in he 3-mm a ea); Kmax (maximum co neal powe in he
8-mm a ea); BFS (bes - i sphe e); CCT (cen al co neal hickness); D (diop e); µm (mic ons)
aPai ed samples - es ; bWilcoxon signed ank es
Va iable Mean±SD P
P eope a i e Pos ope a i e Change
K1 (D) 46.02±3.47 46.01±3.15 -0.01±2.18 0.992a
K2 (D) 51.34±4.55 49.41±3.25 -1.93±3.39 0.050b
K2-K1 (D) 05.32±2.37 03.38±2.41 -1.94±3.50 0.020a
Km (D) 48.49±3.70 47.71±2.97 -0.78±1.98 0.095a
Kmax (D) 57.40±6.44 51.97±4.01 -5.43±5.16 <0.001a
4
Med Su g Oph hal Res
Copy igh © Ja ie González-Pé ez
MSOR.000565. 3(3).2024
An e io BFS (D) 43.55±3.05 42.40±2.24 -1.05±2.56 0.020b
Eccen ici y 0.88±0.32 0.75±0.33 -0.13±0.36 0.079b
CCT (mm) 478±39 487±58 9.10±49.73 0.412a
CTapex (mm) 462±41 478±62 15.95±53.41 0.186a
CTmin (mm) 448±40 461±47 12.90±30.57 0.067a
Figu e 1: Humph ey ec o cylinde compound o he e ac ion showing a ema kable less dispe sion o
pos ope a i e alues.
Table 3: S a is ically signi ican co ela ions o he 6-mon h pos ope a i e ou comes wi h p eope a i e opog aphic,
abe ome ic and Ke a ing segmen pa ame e s.
UDVA (unco ec ed dis ance isual acui y); CDVA (co ec ed dis ance isual acui y); MRSE (mani es e ac i e sphe ical
equi alen ); TKS ( hicke Ke a ing segmen ); K2 (co neal powe in he s eepes 3-mm a ea); K2-K1 (mean co neal
as igma ism in he 3-mm a ea); Km (mean co neal powe in he 3-mm a ea); Kmax (maximum co neal powe in he
8-mm a ea); BFS (bes - i sphe e); CA (co neal as igma ism); RMS ( oo mean squa e); HOA (highe o de abe a ion); D
(diop e); µm (mic ons); Ze nike e ms (Zo de mode)
aPea son co ela ion; bRho Spea man
Va iable Co ela iona,b Co ela ion Coe icien P
Change in CDVA (Snellen)
P eop K2 0.51 0.018a
P eop Km 0.507 0.019a
P eop Kmax 0.502 0.021a
P eop CTapex -0.641 0.002a
P eop CTmin -0.65 0.001a
P eop P ima y Ve ical CA Z2
2-0.78 <0.001a
P eop 4 h-o de sphe ical abe a ion Z4
0-0.54 0.011a
Change in mani es Cylinde (D)
P eop Cylinde -0.657 0.001a
P eop MRSE -0.437 0.047a
P eop K2 0.482 0.027a
P eop kmax 0.582 0.006a
P eop P ima y Oblique CA Z2
-2 -0.444 0.044a
P eop Ho izon al Coma Z2
2-0.574 0.006a
TKS 0.491 0.023a
5
Med Su g Oph hal Res
Copy igh © Ja ie González-Pé ez
MSOR.000565. 3(3).2024
Change in MRSE (D)
P eop Sphe e -0.612 0.003b
P eop Cylinde -0.475 0.029b
P eop MRSE -0.668 0.001b
P eop Ve ical Coma Z3
-1 -0.622 0.003b
Change in Mean Kmax (D)
P eop K2 -0.687 0.001a
P eop K2-K1 -0.643 0.002a
P eop Kmax -0.782 <0.001a
P eop Eccen ici y -0.483 0.027a
P eop 4 h-o de sphe ical abe a ion Z4
00.574 0.007a
Change in Mean K2-K1 (D)
P eop K2 -0.545 0.011a
P eop K2-K1 -0.498 0.022a
P eop Kmax -0.728 <0.001a
Change in Mean BFS (D)
P eop Kmax -0.634 0.002b
P eop 4 h-o de sphe ical abe a ion Z4
00.466 0.033b
P eop RMS HOA -0.437 0.048b
TKS 0.44 0.046b
Change in Ve ical Coma Z3
-1 (mm)
P eop P ima y Oblique CA Z2
-2 0.461 0.035a
P eop Ve ical Coma Z3
-1 0.871 <0.001a
TKS 0.588 0.005a
Change in Oblique T e oil (mm) P eop Sphe e -0.636 0.026a
P eop MRSE -0.583 0.046a
Abe ome ic pa ame e s and pos ope a i e ou comes
Table 4 summa izes abe ome ic da a be o e and 6-mon hs
a e su ge y. A signi ican dec ease was obse ed in he mean
RMS high o de abe a ions alues (P=0.045). The e ical coma,
oblique e oil and oblique co neal as igma ism became, on
a e age, less posi i e a e su ge y (P=0.020, P=0.018 and P<0.01
espec i ely). No signi ican changes we e obse ed in o al RMS
o o he esidual abe a ions. Nega i e signi ican co ela ions
we e ound be ween pos ope a i e change in bes CDVA and
se e al p eope a i e abe ome ic co neal pa ame e s (Table 3),
such as p ima y e ical co neal as igma ism ( =-0.780; P<0.001),
and sphe ical abe a ion ( =-0.540; P=0.011). Figu e 2 shows he
nega i e ela ionship be ween change CDVA and he signi ican
co ela ed abe ome ic ac o s. Simila ly, nega i e co ela ions
we e ound be ween MRSE o change in mani es cylinde and
di e en p eope a i e abe ome ic co neal pa ame e s. Sca e
g ams showing he nega i e ela ionship be ween change in MRSE
o mani es cylinde and p eope a i e coma can be seen in Figu e 3.
Figu e 2: Sca e g ams showing he ela ionship be ween he change in he bes co ec ed dis ance isual acui y
and: A) P eope a i e p ima y e ical co neal as igma ism; B) Sphe ical abe a ion.

6
Med Su g Oph hal Res
Copy igh © Ja ie González-Pé ez
MSOR.000565. 3(3).2024
Table 4: Summa y o he co neal abe ome ic da a a e 6-mon hs Ke a ing implan a ion.
RMS ( oo mean squa e); HOA (highe o de abe a ion); µm (mic ons); Ze nike e ms (Zo de
mode)
aPai ed samples - es
Va iable Mean±SD P
P eope a i e Pos ope a i e Change
RMS HOA (mm) 5.20±1.92 3.98±2.08 -1.22±2.63 0.045a
Ve ical coma Z3
-1 (mm) 3.15±2.50 1.30±1.31 -1.85±1.83 0.020a
Ho izon al coma Z3
1 (mm) 4.99±1.91 4.07±2.92 -0.92±1.16 0.111a
P ima y sphe ical abe a ion Z4
0 (mm) 1.76±2.00 1.54±1.59 -0.22±1.73 0.657a
P ima y Ve ical CA Z2
2 (mm) 4.72±3.81 3.31±4.03 -1.41±1.56 0.171a
P ima y Oblique CA Z2
-2 (mm) 3.02±3.12 0.63±2.54 -2.39±1.86 0.009a
Oblique T e oil Z3
3 (mm) 0.72±1.28 0.14±1.37 -0.58±0.91 0.018a
Figu e 3: Sca e g ams showing he ela ionship be ween: A) The change in mani es e ac i e sphe ical equi alen
and p eope a i e e ical coma; B) The change in mani es cylinde and p eope a i e ho izon al coma.
Discussion
The dec ease in isual quali y in subjec s wi h ke a oconus is
no only due o low-o de abe a ions (sphe o-cylind ical e ac i e
e o ) esul ing om co neal p o usion bu is also due o high-
o de ones. This is p ac ically explained by he ac ha spec acles
in mos cases a e no able o p o ide ull co ec ion. This s udy
e alua ed he e ec o Ke a ings (mechanical implan a ion wi h a
acuum de ice) on isual, e ac i e, opog aphic and abe ome ic
ou comes in pa ien s wi h KC and high myopia 6-mon hs a e ICRS
su ge y.
Visual acui y and e ac i e pa ame e s
The cu en s udy showed a signi ican educ ion in mani es
sphe e, cylinde and sphe ical equi alen which a e in ag eemen
wi h p e ious au ho s [15-20]. Consis en wi h he signi ican
educ ion in e ac ion, ou s udy showed a signi ican imp o emen
om 2 o 3 lines in UCVA and CDVA, which is consis en wi h o he
s udies epo ing g ea e inc ease in UDVA han in CDVA, [16] while
o he au ho s ha e obse ed be e esul s in CDVA han UDVA [17].
Fac o s jus i ying hese di e ences could be a ibu ed o a ia ions
in he s uc u e and hickness o he segmen s, dis ance om he
cen e , as well as o ien a ion and symme y in he inse ion o he
ings [18]. In ac , baseline disease se e i y and he pa e n o ec asia
a e so he e ogeneous in ke a oconic eyes, ha gene aliza ions a e
no possible o may ha e no sense. A signi ican inding in his s udy
is ha isual acui y changes ha e been highe o hose pa ien s
wi h mo e se e e s ages o he disease. This inding ag ees wi h he
cu en app oaches o sequen ial KC ea men ha assumes o he
ea men s o ea ly o ms o KC including co neal c oss-linking
and con ac lenses, lea ing ICRS when he disease is al eady s able
and e en ually mo e ad anced [19]. An imp o emen in UDVA is
a ibu able mos ly o a educ ion in lowe o de abe a ions
(MRSE, sphe e o cylinde ), while an imp o emen in CDVA is
a ibu ed o educ ion in co neal abe a ions (p ima y sphe ical
abe a ion, co neal as igma ism, o coma).
Topog aphic pa ame e s and pos ope a i e ou comes
In he majo i y o s udies, ICRS implan a ion induces a
signi ica i e educ ion in Km and Kmax eadings be ween 2 o 5
7
Med Su g Oph hal Res
Copy igh © Ja ie González-Pé ez
MSOR.000565. 3(3).2024
D, wi h a signi ican as igma ic educ ion be ween 1.5 o 2.75 D,
allowing an imp o emen o isual acui y anging o 1 o 7 lines
in CDVA [9-10,19-21]. This high a ia ion in isual pe o mance
depends on KC s age, cone loca ion, as igma ism cha ac e iza ion
and ICRS ype [19-22]. The p esen in es iga ion shows a no
signi ican Km educ ion by 0.78 D, bu a signi ican Kmax educ ion
by 5.43 D wi h a dec eased co neal as igma ism by close o 2.00
D associa ed wi h as igma ic educ ion by 3.33 D. Associa ed wi h
hose changes, in his s udy, we ound an imp o emen o 0.21
Snellen uni s be ween p e-ope a i e and pos -ope a i e UDVA
which is in ag eemen wi h mos o he e iewed li e a u e [19-
21]. Howe e , Km change in his s udy seems o be lowe han
ha ound by o he au ho s, p obably because we ha e mo e
se e e cases, wi h highe p eope a i e co neal as igma ism and
poo e p e-ope a i e co ec ed and unco ec ed isual acui y, so
he ac o s in ela ion o he cha ac e is ics o he subjec s wi h
KC may be behind hese di e ences. The p esen s udy shows ha
educ ion o co neal as igma ism is he main ac o jus i ying he
imp o emen in isual acui y. This educ ion has been ound in
mos o he eyes (19 ou o 21) excep one eye wi hou measu able
changes and ano he eye wi h a signi ican inc ease in as igma ism.
Reduc ion anged om 0 o 10 D o cylinde . In line wi h a gumen s
o di e en indica ions o di e en s ages o KC, he ole o
ICRS in co neal s abiliza ion has also been objec o in e es by
he oph halmological communi y and has been p oposed ha
maximum cu a u e and hinnes co neal hickness migh be used
as indica o s o KC s abiliza ion/p og ession [23]. In he p esen
s udy, we obse ed a educ ion in Kmax and an inc ease in he
co neal hickness pa ame e s. Howe e , as we did only make a
single measu emen a e su ge y, he p esen s udy canno e i y
he e ec o ICRS in co neal s abili y o e ime due o he ela i ely
sho ollow-up pe iod. Se e al s udies in es iga ing he po en ial
ole o ICRS in disease s abiliza ion ound ha implan a ion o ICRS
does no signi ican ly in luence p og essi e ke a oconus in young
pa ien s wi h con i med p og ession o he disease [24-26]. Since
o he au ho s ound ICRS implan a ion o be a s able p ocedu e o
es o ing ision in pa ien s wi h KC, his ma e should be u he
in es iga ed [27].
Finally, because o he la ening induced by his echnique,
he e is ano he impo an bene icial ou come. Conside ing he
limi ed imp o emen in UDVA and CDVA ob ained by he ICRS
implan a ion, con ac lenses a e usually necessa y o complemen
he ehabili a ion. This s a egy has p o ed o be success ul
in p e ious publica ions, using di e en ma e ials and i ing
app oaches [28-29]. The opog aphic indings om his s udy migh
be also ele an on his ega d as we ha e ound a educ ion in
maximum ke a ome ic eading and educ ion in an e io co neal
as igma ism. This migh ha e implica ions in con ac lens i ing a
di e en le els. Fi s , he la ening e ec obse ed in he la ening
o he s eepes me idian by 1.90 D and by o e 5.50 D in he Kmax
pa ame e . This la ening is also obse ed in he BFS pa ame e
wi h a educ ion o nea ly 1.00 D. This ep esen s a la ening o
he o e all co neal cu a u e ha migh imp o e he i ing o a
co neal igid gas pe meable con ac lens. Second, educ ion o
an e io co neal as igma ism nea ly 2.00 D migh also imp o e he
i ing o he con ac lens as i is usual o ind a s eep i ing along
he la es me idian. F om he i ing poin o iew, we hypo hesize
ha a educ ion o nea ly 0.20 mm in he s eepes cu a u e, 0.40
mm in co neal as igma ism migh imp o e co neal lens i ing.
Howe e , we acknowledge ha he p esence o he ICRS, hickening
he mid-pe iphe al co nea, migh also p esen a challenge o he
i ing as he loca ion o hese segmen s migh c ea e a mechanical
con lic wi h he unde lying co neal issue. Howe e , his migh be
o e come using la ge diame e lenses suppo ed by he pe iphe al
co nea ou side he 5-6 mm o he ICRS unnel.
Abe ome ic pa ame e s and pos ope a i e ou comes
When co neal abe a ions we e analyzed, e ical coma, p ima y
oblique co neal as igma ism and e oil dec eased 6-mon hs a e
su ge y, as he main abe ome ic changes ound in his s udy. In
addi ion, we ound a signi ican pos ope a i e RMS HOA a 6 mm
imp o emen while no changes we e obse ed in o he esidual
abe a ions which suppo s he indings o some au ho s and
con adic s o he s [15,20]. The p edominan abe ome ic de ec in
KC is he coma abe a ion, pa icula ly i s e ical componen , such
is he case ha Alió and Shabayek used his pa ame e o modi y
he classic Amsle -K umeich classi ica ion o KC, in oducing coma
abe a ion as one o he indica o s [30]. Coma has been ound o be
dec eased in he sho - e m and he long- e m pe iods a e ICRS
implan a ion [8,17,21]. Since di e en au ho s ha e demons a e
ha coma has a nega i e e ec on isual acui y [24], he educ ion
in coma abe a ion, especially in e ical coma, migh also explain
he imp o emen in CDVA ound in his in es iga ion, which is in
ag eemen wi h o he au ho s [20,23,25]. Howe e , he e a e o he
s udies epo ing no signi ican changes in any co neal abe ome ic
pa ame e a e ICRS implan a ion by mechanical unneliza ion,
which is con adic o y o he indings o he p esen s udy [15].
Tha s udy ound ha mechanical unneliza ion speci ically o
In acs implan a ion in eyes wi h ea ly o mode a e KC has limi ed
he po en ial abe ome ic co ec ion because he p ocedu e i sel
gene a ed new abe a ions, pa icula ly nega i e p ima y sphe ical
abe a ion, and p ima y coma, bu his end was no speci ically
con i med o Ke a ings because he limi a ions o he s udy o
his segmen ype. O he ac o s could explain hese di e ences,
o example, we may ha e included mo e mode a e and se e e
cases and obse ed less complica ions compa ed wi h p e ious
s udies. Ano he possible explana ion, as men ioned abo e, could
be he cha ac e is ics o he segmen s as well as o ien a ion and
symme y in he ICRS inse ion [18,26].
Limi a ions
A limi a ion o his s udy is he educed sample size. Howe e ,
based on ou ini ial es ima ions, he sample was powe ed o
obse e a leas 1 line o imp o emen in isual acui y wi h 18
eyes en olled. A u he limi a ion migh be conside ed he ac
ha he implan a ion mode has been manual while em osecond
lase -assis ed echnology migh be conside ed he e e ence
o ICRS implan a ion. In ac , em osecond lase can assis in a
be e p edic ion o he dep h and a ea o implan a ion, minimizes
p ocedu e du a ion, and educes he isk o in lamma ion, bu
8
Med Su g Oph hal Res
Copy igh © Ja ie González-Pé ez
MSOR.000565. 3(3).2024
p e ious esea ch has ailed o demons a e supe io i y in isual
ou comes when compa ed wi h manual implan a ion [15]. In
addi ion, an al e na i e o he manual app oach is o use a acuum
de ice, such as he employed in his s udy o s abilize he globe
du ing c ea ion o he co neal unnel o ob ain be e isual acui y
and mo e con olled co neal shape, howe e mo e esea ch is
equi ed in his a ea o e alua e and compa e he clinical ou comes.
Fu he mo e, we bea in mind ha s ill nowadays mos o he
implan a ions a e made wi h manual echnique including many
e ia y e e ence hospi als as is ou case.
In conclusion, analysis o he ou comes a e Ke a ings
implan a ion showed a signi ican pos ope a i e co neal la ening
wi h a subsequen inc ease in UCVA and CDVA. Visual, e ac i e,
opog aphic and abe ome ic pa ame e s ema kably change in
he 6-mon h pe iod a e Ke a ing ICRS implan a ion. Co ela ions
be ween isual ou comes and p eope a i e pa ame e s sugges a
s onge e ec in KC pa ien s wi h highe K2, Km o Kmax alues as
well as highe as igma ism, coma, and sphe ical abe a ion, which
imply pa ien s wi h mo e se e e s ages o he disease.
Re e ences
1. Da idson AE, Hayes S, Ha dcas le AJ, Tu SJ (2014) The pa hogenesis o
ke a oconus. Eye 28(2): 189-95.
2. Alio JL, Vega-Es ada A, Sanz-Diez P, Peña-Ga cía P, Du án-Ga cía ML, e
al. (2015) Ke a oconus managemen guidelines. In e n J Ke a oconus
Ec a ic Co neal Dis 4: 1-39.
3. Vega-Es ada A, Alio JL (2016) The use o in aco neal ing segmen s in
ke a oconus. Eye Vis 3: 8.
4. Jhanji V, Sha ma N, Vajpayee RB (2011) Managemen o ke a oconus:
Cu en scena io. B J Oph halmol 95(8): 1044-50.
5. Giacomin NT, Mello GR, Medei os CS, Alyin Kiliç, C islaine CS, e al.
(2016) In aco neal ing segmen s implan a ion o co neal ec asia. J
Re ac Su g 32(12): 829-39.
6. Colin J, Cochene B, Sa a y G, Male F (2000) Co ec ing ke a oconus
wi h in aco neal ings. J Ca a ac Re ac Su g 26(8): 1117-22.
7. She y R, Ku ian M, Anand D, P e na M, KM Na ayana, e al. (2008) In acs
in ad anced ke a oconus. Co nea 27(9): 1022-9.
8. Kymionis GD, Siganos CS, Tsiklis NS, A Anas asakis, Sonia HY, e al.
(2007) Long- e m ollow-up o In acs in ke a oconus. Am J Oph halmol
143(2): 236-44.
9. Za e MA, Hashemi H, Sala i MR (2007) In aco neal ing segmen
implan a ion o he managemen o ke a oconus: Sa e y and e icacy. J
Ca a ac Re ac Su g 33(11): 1886-1891.
10. Daxe A, Mahmoud H, Venka eswa an RS (2010) In aco neal con inuous
ing implan a ion o ke a oconus: one-yea ollow-up. J Ca a ac Re ac
Su g 36(8): 1296-1302.
11. Le inge S, P ok oy R (2005) Ke a oconus managed wi h In acs: One-
yea esul s. A ch Oph halmol 123(10): 1308-1314.
12. Daxe A (2008) Co neal in as omal implan a ion su ge y o he
ea men o mode a e and high myopia. J Ca a ac Re ac Su g 34(2):
194-198.
13. Abd Elaziz MS, El Saebay Sa han AR, Ib ahim AM, Elsha y Haggag HA
(2018) An e io segmen changes a e em osecond lase -assis ed
implan a ion o a 355-deg ee in as omal co neal ing segmen in
ad anced ke a oconus. Co nea 37(11): 1438-1443.
14. Hashemian SJ, Fa shchian N, Fo ou am-Jazi A, Ja a i ME, Hashemian MS,
e al. (2018) Visual and e ac i e ou comes and omog aphic changes
a e em osecond lase -assis ed in as omal co neal ing segmen
implan a ion in pa ien s wi h ke a oconus. J Oph halmic Vis Res 13(4):
376-382.
15. Piñe o DP, Alio JL, El Kady B, E ekan C, Hec o M, e al. (2009)
Re ac i e and abe ome ic ou comes o in aco neal ing segmen s
o ke a oconus: mechanical e sus em osecond-assis ed p ocedu es.
Oph halmology 116(9): 1675-1687.
16. Heikal MA, Abdelsha y M, Soliman TT, Hamed AM (2016) Re ac i e
and isual ou comes a e ke a ing in as omal co neal ing segmen
implan a ion o ke a oconus assis ed by em osecond lase a 6 mon hs
ollow-up. Clin Oph halmol 11: 81-86.
17. Fahd DC, Jabbu NS, Awwad ST (2012) In as omal co neal ing
segmen SK o mode a e o se e e ke a oconus: A case se ies. J Re ac
Su g 28(10): 701-705.
18. Tu KL, Sebas ian RT, Owen M, Ba e bu y M, Kaye SB (2011)
Quan i ica ion o he su gically induced e ac i e e ec o in as omal
co neal ing segmen s in ke a oconus wi h s anda dized incision si e
and segmen size. J Ca a ac Re ac Su g 37(10): 1865-1870.
19. Gomes JA, Tan D, Rapuano CJ, Michael WB, Rena o A, e al. (2015) Global
consensus on ke a oconus and ec a ic diseases. Co nea 34(4): 359-69.
20. Cos a JV, Mon ei o T, F anquei a N, Fa ia-Co eia F, Al onso J, e al. (2021)
Fi e-yea long- e m ou comes o in as omal co neal ing segmen
implan a ion using he manual echnique o ke a oconus managemen .
J Ca a ac Re ac Su g 47(6): 713-721.
21. Vega-Es ada A, Alió JL, B enne LF, Bu gue a N (2013) Ou comes o
in as omal co neal ing segmen s o ea men o ke a oconus: Fi e-
yea ollow-up analysis. J Ca a ac Re ac Su g 39(8): 1234-40.
22. Pé ez-G acia J, Á ila FJ, A es J, Vallés JA, Remón L (2020) Misalignmen
and il e ec on asphe ic in aocula lens designs a e a co neal
e ac i e su ge y. PLoS One 15(12): e0243740.
23. Al onso JF, Fe nández-Vega-Cue o L, Lisa C, Mon ei o T, Mad id-Cos a
D (2019) Long- e m ollow-up o in as omal co neal ing segmen
implan a ion in pedia ic ke a oconus. Co nea 38(7): 840-846.
24. Alejand e N, Pé ez-Me ino P, Vela de G, Jiménez-Al a o I, Ma cos S (2022)
Op ical e alua ion o in aco neal ing segmen su ge y in ke a oconus.
T ansl Vis Sci Technol 11(3): 19.
25. Fe nández-Vega Cue o, Lisa C, Poo-López A, Mad id-Cos a D, Me ayo-
Llo es J, e al. (2016) In as omal co neal ing segmen implan a ion in
409 pa acen al ke a oconic eyes. Co nea 35(11): 1421-1426.
26. Fe nández-Vega-Cue o L, Lisa C, Al onso-Ba olozzi B, Mad id-Cos a D,
Al onso JF (2021) In as omal co neal ing segmen implan a ion in
pa acen al ke a oconus wi h pe pendicula opog aphic as igma ism
and coma ic axis. Eu J Oph halmol 31(4): 1540-1545.
27. Schneide de A aujo, Kubo L, Ma inho DR, Kwi ko S (2020) Ke a oconus
p og ession a e in as omal co neal ing segmen implan a ion
acco ding o age: 5-yea ollow-up coho s udy. In Oph halmol 40(11):
2847-2854.
28. Downie LE, Lindsay RG (2015) Con ac lens managemen o ke a oconus.
Clin Exp Op om 98(4): 299-311.
29. Se ami o-Blanco M, Ca pena-To es C, Ca ballo J, Piñe o D, Lipson
M, e al. (2019) An e io co neal cu a u e and abe a ion changes
a e scle al lens wea in ke a oconus pa ien s wi h and wi hou ing
segmen s. Eye Con ac Lens 45(2): 141-148.
30. Alió JL, Shabayek MH (2006) Co neal high o de abe a ions: A me hod
o g ade ke a oconus. J Re ac Su g 22(6): 539-545.