INTERNATIONAL JOURNAL OF HEALTH & MEDICAL RESEARCH
ISSN(p in ): 2833-213X, ISSN(online): 2833-2148
Volume 04 Issue 11 No embe 2025
DOI : 10.58806/ijhm .2025. 4i11n07
Page No. 631 - 640
631Page www.ijhm .com 5 22011 No embe Issue 4Volume 0 IJHMR,
Mo phome ic S udy o he Op ic Ne e Head Among No he n Nige ian
Adul s, Using Op ical Cohe ence Tomog aphy
Nu addeen Jaa a Ib ahim1*, Sanusi Muhammad Bello1, P ashan h Kuma Ka a2, Ta ig Hussain
Abdel ahman1, Sadiq Hassan3, Sauda Ga ba Habib3
1 Depa men o Biomedical Sciences, College o Den is y, King Faisal Uni e si y, Al-Ahsa 31982, Saudi A abia
2 Depa men o Res o a i e Den al Sciences, College o Den is y, King Faisal Uni e si y, Al-Ahsa 31982, Saudi A abia
3Depa men o Oph halmology, Facul y o Clinical Sciences, College o Heal h Sciences, Baye o Uni e si y Kano, Kano, Nige ia
ABSTRACT: Glaucoma is a common heal h p oblem wo ldwide especially in adul popula ion. I is cha ac e ised by p og essi e
i e e sible op ic ne e head (ONH) damage, due o al e a ions in e inal ganglion cells nu i ion and iabili y. Ea ly diagnosis is
key o be e managemen and p ognosis. This s udy measu es he ONH pa ame e s among adul s in no he n Nige ia, using Op ical
cohe ence omog aphy (OCT). This would p o ide a e e ence alues o ONH pa ame e s ha would help clinicians obse e ea ly
abno mal op ic ne e changes o ea ly diagnosis o glaucoma among he popula ion. Heal hy 770 adul olun ee s om e hnic
no he n Nige ians unde wen comple e ocula examina ion, including an e io and pos e io segmen examina ion. Those wi h
no mal indings p oceeded o ha e op ic ne e head examina ion using a S a us OCT machine. The ONH pa ame e s analysed
we e; op ic disc a ea (DA), im a ea (RA), cup a ea (CA), and cup- o-disc a io (CDR). The mean DA, RA, and CDR ound in he
s udy we e 2.35mm2 SD=+0.88, 1.76mm2 SD=+0.43, and 0.44 SD=+0.21, espec i ely. The DA and CDR we e signi ican ly la ge
wi h age (p=0.001) and he RA was ound o signi ican ly decline wi h age. A eg ession o mula was de i ed o use o he
es ima ion o ONH dimensions based on age. This s udy p o ided e e ence alues o he ONH pa ame e s among he no he n
Nige ians. We also ob ained a eg ession model ha could be used o es ima e di e en ONH dimensions om indi idual’s age,
wi h a eliable accu acy. This would enable an e hnic speci ic sc eening p o ocol o clinicians in sc eening, diagnosis, and
managemen o op ic neu opa hies like glaucoma.
KEYWORDS: Op ic ne e head, Op ical Cohe ence Tomog aphy, Disc a ea, Cup-disc a io, im a ea, Cup a ea, Glaucoma.
SYNOPSIS
Glaucoma is a p og essi e disease a ec ing he op ic ne e head. This s udy analyses he op ic ne e head o heal hy indi iduals o
p o ide no ma i e e e ence alues and an age-based es ima es o he ne e head dimensions impo an o sc eening and moni o ing
pu poses.
INTRODUCTION
Op ic ne e head (ONH) is also e med he op ic disc, papilla o simply he disc. I is he e y beginning o he op ic ne e, he 2nd
c anial ne e ha is isible on e inal examina ion [1]. Axons o he e inal ganglion cells o m ne e bundles ha con e ge on he
ONH in ou zones (supe io , in e io , medial and la e al) and exi he eye pos e io ly h ough he lamina c ib osa o he scle a o
become he op ic ne e. The e is a cen al pale dep ession o he disc e med he op ic cup. This con ains no e inal issue and ba es
he cen al e inal essels (a e y and ein). The a ea be ween he cen al cup and ma gins o he disc is he neu o- e inal im (NRR).
I looks pinkish ed oph halmoscopically as i con ains ne e ib es wi h ine capilla y ne wo k [2].
Mo phome y o he ONH pa ame e s is used o co ela e no mal om pa hologic condi ions o he op ic ne e ha occu in a a ie y
o op ic ne e diseases like glaucoma, colobomas and comp essi e neu al lesions [2]. Such pa ame e s a e disc a ea (DA), NRR
a ea (RA), NRR hickness, cup a ea (CA), e ical cup o disc a io ( CDR), and pe i-papilla y ne e ib e laye hickness.
P ima y e inal lesions, neu o-oph halmic condi ions o p ima y op ic ne e diso de s p esen wi h cha ac e is ic ONH indings ha
enable making diagnoses and moni o ing p og ession o hese diso de s [3].
In glaucoma, a disease wi h cha ac e is ic op ic ne e neu opa hy, he e is i e e sible dea h and loss o e inal ganglion cells. The
pa hogenesis is s ill no e y clea bu is ela ed o ele a ed eye p essu e. I is howe e p o ed ha mo e han a hi d o glaucoma
pa ien s ha e no mal o e en low eye p essu e. This b ough o he knowledge o ‘no mal p essu e glaucoma’ which is linked o
imbalance be ween neu al p o ec i e mechanisms p o ided by a ious neu al g ow h ac o s. Diagnosis and moni o ing o glaucoma
Mo phome ic S udy o he Op ic Ne e Head Among No he n Nige ian Adul s, Using Op ical Cohe ence
Tomog aphy
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in ol e de ec ing changes on he ONH which could ini ially be sub le and di icul o ecognize om he no mal [4]. Di e en
s udies ha e shown a ia ions in he opog aphy o he ONH among aces [4-6] and gende [7-10].
E alua ion o he ONH can be done using quali a i e echniques which a e clinical oph halmoscopy and s e eopho og aphy [8].
These me hods a e subjec i e, wi h high in e obse e a iabili y. Quan i a i e e alua ion using imaging echniques like op ical
cohe ence omog aphy (OCT) gi es accu a e and mo e objec i e measu emen s. This helps in ea ly de ec ion o op ic disc and
e inal diso de s, p o iding means o ea ly diagnosis and objec i e moni o ing o abno mali ies like glaucoma [3].
Op ical cohe ence omog aphy is a non-con ac , non-in asi e imagine echnique which p o ides in i o c oss-sec ional image o
he a ious pa s o he e ina including he ONH ha a e ep oducible, quan i a i e and objec i e [11]. The OCT machine is a
compu e assis ed op ical ins umen ha uses he p inciple o low cohe ence in e e ome y o measu e he echo ime delay and
in ensi y o backsca e ed and back- e lec ed ligh o m in e nal mic os uc u e in biological issues. In he eye, i p o ides c oss
sec ional images o he op ic ne e head and he e ina wi h high esolu ion omog aphic sec ions wi h <10 µm axial esolu ion [12].
As he e is no in o ma ion eadily a ailable abou he no mal alues o he op ic ne e head in no he n Nige ian popula ion, his
s udy aimed o p o ide hese alues among adul Nige ians. Clinicians can use his in o ma ion as e e ences in making ea ly
diagnosis o glaucoma and o he op ic ne e diseases.
METHODOLOGY
S udy se ings
This c oss-sec ional s udy was ca ied ou on olun ee adul s a he eye clinic o Amina Kano Teaching hospi al, no he n Nige ia.
E hical app o al was ob ained om he ins i u ional e hical boa d o he eaching hospi al and Baye o uni e si y, Nige ia. All
subjec s p o ided e bal and endo sed w i en consen o ensu e olun a y pa icipa ion. The subjec ’s in o ma ion was handled
wi h u mos con iden iali y by anonymizing all da a ob ained ha will expose an indi idual’s iden i y. Such in o ma ion was only
made a ailable o au ho ize pe sonnel. All he examina ions and in es iga ion p ocedu es conduc ed we e done ee o cha ge.
S udy Loca ion and sample selec ion
The s udy was conduc ed a he oph halmic clinic o he eaching hospi al, ex ending o e a pe iod o 8 mon hs. The minimum
sample size was de e mined by he o mula:
n = (Z² x P x (1-P)
e²
Whe e
n = minimum sample size
Z = Z sco e a 95% con idence in e al (1.96)
P = p e alence 50%
e = ma gin o e o (used he e as 5%)
n = (1.96)² x 0.3 x (1-0.5)
(0.05)²
Minimum sample size (n) = 384
In o de o ob ain mo e obus da a o analysis we conduc ed a sys ema ic andom sampling and selec ed 770 olun ee s. These
included ela i es o pa ien s a ending he clinic and hospi al s a , ha ul illed he s udy c i e ia and we e en olled as he s udy
pa icipan s. All he selec ed samples had o be o Hausa descen (ensu ed by a g and pa en age), om he no he n Nige ia, aged
18 o 60 yea s and ee o sys emic medical and/o ocula complain s o abno mal indings.
Examina ion
De ailed medical his o y ega ding sys emic condi ions, and se e al isk ac o s associa ed wi h glaucoma and e inal disease
including hype ension, diabe es melli us, hea disease, and ascula disease like sickle cell disease we e ob ained. All subjec s
unde wen a comple e eye examina ion ha included measu emen o Snellen bes -co ec ed isual acui y, sli lamp biomic oscopy,
gonioscopy, applana ion onome y, lens opaci y es ima ion wi h e sion III o he Lens Opaci ies Classi ica ion Sys em g ading
sys em [13]. An e io segmen o he eye was examined using he sli lamp biomic oscope (Keele , 2000 model). Pos e io segmen
examina ion was done using +78D condensing lens wi h he sli lamp and Keele di ec oph halmoscope. In aocula p essu e (IOP)
was measu ed by a Goldmann applana ion onome e , which is moun ed on he sli lamp machine. Topical 0.5% p opa acaine
chlo ide was ins illed in he eye as a su ace anaes he ic agen . In subjec s ha we e no coope a i e, IOP was measu ed wi h he
Keele ai pu non-con ac applana ion onome e .
Exclusion c i e ia
Volun ee s wi h his o y o glaucoma, p e ious eye auma o su ge y, hose wi h sys emic diseases like diabe es melli us,
hype ension o sickle cell disease. O he exclusion c i e ia we e unco ec ed VA o <6/12, anisoco ia mo e han 3mm, hazy media,
na ow an e io chambe angle, IOP > 21mmHg, o pos e io segmen pa hology no iced on undoscopy.
Mo phome ic S udy o he Op ic Ne e Head Among No he n Nige ian Adul s, Using Op ical Cohe ence
Tomog aphy
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Op ic Ne e Head OCT Measu emen s
Subjec s ha ul illed he abo e c i e ia we e scheduled o OCT p ocedu e. The ONH measu emen was pe o med using Time
domain S a us OCT machine (model 3000, e sion 4.0). The s eps o he p ocedu e we e ully explained o he subjec s. Bo h eyes
we e scanned, igh hen le . Subjec would be examined si ing up igh , head i ed o he head es and eyes aligned o he beam
sou ce. The op ic ne e head was scanned using he as scan ONH p o ocol by clicking on he ‘ONH’ icon which would be
highligh ed, as desc ibed by Mansoo i.[14] Signal s eng h o accep able quali y, 7 and abo e was accep ed and p in ed ou .
O he wise, a signal o < 6 would be disca ded and he ONH e- scanned. The OCT machine has an inbuil so wa e ha p o ided a
measu emen o he op ic ne e pa ame e s. I hen analyzed hese measu emen s and c ea ed a nume ic and pic o ial image o he
ONH dimensions (Fig. 1: Op ical Cohe ence Tomog aphy image o he ONH).
S a is ical analysis
Da a was analysed using IBM S a is ical Package o Social Sciences (SPSS, USA e sion 23.0;). Op ic ne e head pa ame e s
analysed; disc a ea (DA), im a ea (RA), cup a ea (CA) and cup o disc a io (CDR). Con inuous a iables we e exp essed as
minimum, maximum and mean + s anda d de ia ion (SD). Compa ison o he means o disc pa ame e s be ween gende and be ween
igh and le eyes was examined using S uden ’s (independen ) - es . Mean di e ence o he disc pa ame e s we e compa ed among
di e en age g oups using one-way analysis o a iance (ANOVA), ollowed by pos - hoc es o mul iple compa isons. Linea
eg ession was conduc ed o ob ain eg ession models o p edic ing ONH dimension. Age was used as he p edic o o ONH
dimension which we e he dependen a iables. P < 0.05 was se as a le el o s a is ical signi icance
RESULTS
A e en y and cleaning, he da a o 770 subjec s was ob ained and p ocessed o analysis. Subjec s we e aged be ween 18 and 61
yea s wi h majo i y (68%) being males and he emainde we e emales. Male o emale a io was 2.1: 1. Subjec s we e g ouped
in o h ee age ca ego ies <30 yea s, 30 – 50 yea s and >50 yea s.
Figu e 1: Op ical Cohe ence Tomog aphy image o he ONH
Table 1 shows he desc ip i e s a is ics o disc pa ame e (disc a ea, im a ea, cup a ea and CDR) in all he subjec s. The mean disc
a ea was ound o be 2.35mm2 +SD 0.88. The mean im a ea and cup a ea we e 1.76mm2 +SD 0.40 and 0.59mm2 +SD0.20
espec i ely. The e ical cup o disc a io ( CDR) mean alue obse ed was 0.44 +0.19 SD wi h a ange o 0.24 o 0.75.
Mo phome ic S udy o he Op ic Ne e Head Among No he n Nige ian Adul s, Using Op ical Cohe ence
Tomog aphy
634Page www.ijhm .com 5 22011 No embe Issue 4IJHMR, Volume 0
Table 1: Desc ip i e s a is ics o disc pa ame e s in all subjec s
Disc pa ame e (mm)
Minimum
Maximum
Mean
+S. D
Disc a ea
1.60
3.53
2.35
0.88
Rim a ea
1.00
3.03
1.76
0.40
Cup a ea
0.21
1.50
0.59
0.20
Ve ical Cup disc a io
0.24
0.75
0.44
0.19
To compa e he mean di e ence o he op ic disc pa ame e s be ween le and igh eyes, an independen - es was pe o med and
esul shown in Table 2. The means o all disc pa ame e s, excep o CDR, we e obse ed o be highe in he le side. The mean
di e ence was no ound o be s a is ically signi ican in all subjec s. Mean CDR was ound o be simila (mean= 0.44) in bo h
eyes (p=0.84, = -0.21).
Table 2: Compa ison o disc pa ame e s be ween igh and le eyes in all subjec s
Va iables
Righ
(n=770)
Le
(n=770)
P alue
Disc a ea
2.34
2.37
-0.61
0.54
Rim a ea
1.76
1.79
-0.46
0.96
Cup a ea
0.58
0.59
-0.56
0.61
Ve ical Cup
disc a io
0.43
0.44
-0.21
0.84
Table 3 shows he compa ison o mean di e ence o he disc pa ame e s be ween males and emales as es ed by independen - es .
Male subjec s we e ound o ha e s a is ically signi ican la ge disc a ea, im a ea and CDR han he emale subjec s. Mean
di e ence o cup a ea be ween he males and he emales was no s a is ically signi ican .
Table 3: Compa ison o disc pa ame e s be ween male and emale subjec s
Disc pa ame e
Male (n=524)
Female (n=246)
- es
p- alue
Min
Max
Mean
Min
Max
Mean
Disc a ea
1.80
3.53
2.38
1.60
3.58
2.29
2.80
.005
Rim a ea
1.00
3.01
1.78
1.00
3.03
1.70
2.33
.021
Cup a ea
0.21
1.50
0.59
0.20
1.20
0.58
0.90
.362
Ve ical Cup
disc a io
0.24
0.70
0.45
0.24
0.75
0.43
2.18
.033
Figu es 2 and 3 show he dis ibu ion o he ONH dimensions h ough he di e en age g oup ca ego ies. Compa ison o he mean
di e ences o he a iables among age g oups es ed using he one-way ANOVA is ep esen ed in able 4.
Mo phome ic S udy o he Op ic Ne e Head Among No he n Nige ian Adul s, Using Op ical Cohe ence
Tomog aphy
635Page www.ijhm .com 5 22011 No embe Issue 4IJHMR, Volume 0
Figu e 3: Dis ibu ion o ONH dimension ac oss age g oups
Mean disc a ea was ound o be highes among he olde subjec s, which was ound o be s a is ically signi ican di e ence (F=8.54,
p= 0.001). The pos - hoc mul i-compa ison es shows ha de ia ion o he mean disc a ea was s a is ically signi ican (p<0.05)
be ween he age g oups o <30 yea s and >50 yea s.
Figu e 4: Age g oup ca ego y based on ONH dimension
No signi ican di e ence was obse ed in he CA ac oss he age g oups. Olde subjec s we e ound o ha e la ge DA and CDRs
wi h s a is ically signi ican di e ences in he means shown be ween hose in he age g oup <30 yea s, 30 – 50 yea s and >50 yea s
(Table 4).
Table 4: Mean di e ence o disc pa ame e s among he age g oups
Va iable (mm)
<30 yea sn = 378
30 – 50 y s n = 248
>50 n = 144
P alue
Disc a ea
2.14 (0.72)
2.60 (0.92)
3.07(0.35)
8.54
0.012*
Rim a ea
1.82 (0.21)
1.69(0.08)
1.09(0.61)
5.64
0.011*
Cup a ea
0.57 (0.05)
0.56(0.18)
0.59 (0.03)
3.42
0.612
Ve ical CDR
0.37
0.45
0.61
2.56
0.001
2.14
1.82
0.57
0.37
2.8
1.69
0.56
0.45
3.07
1.28
0.59
0.61
DA RA CA VCDR
<30 30 - 50 >50
2.14
2.6
3.07
1.82
1.69
1.28
0.57
0.56
0.59
0.37
0.45
0.61
< 30
30 -50
> 50
DA RA CA CDR
Mo phome ic S udy o he Op ic Ne e Head Among No he n Nige ian Adul s, Using Op ical Cohe ence
Tomog aphy
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The e was a s eady decline obse ed in he neu o- e inal im hickness (RA) wi h age, he highes man ob ained among he younges
subjec s and lowes among he olde subjec s. The ANOVA es ( able 4) shows a signi ican di e ence be ween he age g oups
(F=5.64, p= 0.01). The pos - hoc mul i-compa ison es shows ha he di e ence o he mean im a ea was s a is ically signi ican
be ween he age g oups o <30 and hose 50 yea s and abo e.
Table 5 shows he eg ession equa ion models de i ed om linea eg ession analysis o p edic ion o he ONH a iables using age
as he p edic o . I also shows he R2 alue which is he pe cen age p edic ion accu acy, and he s anda d e o o es ima e (SEE)
which is di e ence be ween he es ima ed and obse ed p edic ed alues. As shown in he able, he e is s ong posi i e co ela ion
be ween DA, CA and CDR wi h age. I also shows a nega i e s ong posi i e co ela ion be ween CDR wi h age indica ing
hinning o he RA wi h inc easing age. The R2 alue o DA, RA, CA and CDR s ood a 50%, 46%, 11%, and 64% espec i ely.
This indica es ha using age as p edic o one can ge 50%, 45% and 64% accu acy in p edic ing DA, RA and CDR o an indi idual.
The SEE obse ed showed low alues (3.44, 3.75, 4.45) indica ing good model p edic ion abili y o DA, RA and CDR
espec i ely. All he eg ession ela ionships we e s a is ically signi ican (p<0.05) excep o ha o CA (p=0.52).
Table 5: Reg ession equa ions o es ima ion o ONH dimension using age as p edic o
ONH Va iables
R2
Reg ession Equa ion
y = mx + c
SEE
P alue
Disc a ea
0.71
0.50
DA = Age x 0.05 + 1.05
3.44
0.02*
Rim a ea
– 0.68
0.46
RA = Age x-0.02 + 2.5
3.75
0.01*
Cup a ea
0.33
0.11
CA = Agex0.66 + 1.51
7.76
0.72
Ve ical CDR
0.80
0.64
CDR= Agex0.015– 0.15
4.45
0.02*
DISCUSSION
P ima y open-angle glaucoma (POAG) is conside ed a e y common cause o p og essi e i e e sible blindness, and he e o e ea ly
diagnosis is a key ac o in he managemen o he disease. Assessmen and analysis o he op ic ne e head pa ame e s is employed
as a non-in asi e ool o ea ly de ec ion o he disease. Va ious s udies e alua ed he op ic ne e head (ONH) opog aphy using
di e en examina ion me hods, p o iding alues o he ONH indices based on he e hnici y, gende , and he echnique used in he
analysis [2,7,15]. This s udy p esen ed no ma i e alues o he ONH pa ame e s in adul Hausa e hnics om no he n Nige ians,
using op ical cohe ence omog aphy (OCT) scans.
The mean op ic disc a ea ound in his s udy (2.35 mm² + 0.88) was highe han ha epo ed in some s udies a ound he wo ld. Fo
example, a s udy in he Ne he lands obse ed a disc a ea o 1.89 mm² among he whi e s udied popula ion [8]. Simila ly, some
s udies obse ed disc a eas smalle han hose ound in his s udy o 1.83 mm² and 1.82 mm², espec i ely [16,17]. This di e ence
may be because hese s udies used spec al domain OCT machine, whe eas in his s udy we used he S a us OCT ype. In
Swi ze land, a s udy epo ed a mean disc a ea lowe han ha ob ained in his s udy [18]. Thei alues a e almos simila o ha
epo ed as pa o he Sydney Adolescen Vascula Eye (SAVE) s udy o 1.98 mm² [19]. These wo s udies had much la ge samples
han he p esen s udy. Mo e impo an ly, hey used Heidelbe g Re ina Tomog aphy (HRT) scanning lase oph halmoscopy (cSLO)
o op ic disc e alua ion, so hei igu es may no be en i ely compa able o ou indings. Simila ly, a s udy conduc ed in Japan
among Hispanics epo ed lowe disc a eas (2.15 mm²) han ha epo ed in his s udy [20]. The acial di e ence may accoun o
his di e ence, bu a di e en OCT p o ocol (combined ONH/RNFL) was used in he abo e esea ch as agains s a us OCT used
in his s udy. Adjus men o he measu ed e ac i e e o o eyes was p oposed o in luence mean disc a ea as sugges ed by a s udy
conduc ed among adul s in Tu key [21]. They showed ha his adjus men esul s in ob aining a smalle mean disc a ea. This
adjus men was no done in his s udy.
Mean disc a ea ob ained in his s udy is close o wha was ob ained by a s udy among Hispanics (2.32 mm²), using a s a us as
ONH p o ocol [6]. Addi ionally, he s udy ound la ge discs in hei A ican Ame ican subjec s (2.40 mm²) han wha hey ob ained
among he whi e subjec s (2.29 mm²). Howe e , he di e ence obse ed be ween he s udies could ha e esul ed om he ac ha
mos o he Black subjec s we e associa ed wi h he myopic e ac i e e o .
The Ro e dam Eye S udy [22], ha used a s e eo-disc analyse in e alua ing he ONH a he han OCT, epo ed a disc a ea o 2.42
mm². This me hod may be a ec ed by image magni ica ion, possibly esul ing in ob aining la ge alues han hose o OCT. Mansoo
[23], also in India, ob ained a highe mean disc a ea (3.36 mm²) han ou inding. As hese abo e s udies used s a us OCT machine
like he one used in his s udy and ob ained la ge disc a eas, e hnic di e si y and gene ic makeup may, he e o e, be a possible
explana ion o he di e ence. Simila ly, esea che s in Egyp epo ed a la ge mean disc a ea o 2.51 mm² using HRT in he
Egyp ian popula ion [2]. In his la e s udy, howe e , he ca ego ies o subjec s ec ui ed we e bo h hose wi h heal hy and hose
wi h ‘suspicious’ op ic discs, and hey had a much smalle sample size (100 subjec s) han ou s udy o 770 subjec s.
Mo phome ic S udy o he Op ic Ne e Head Among No he n Nige ian Adul s, Using Op ical Cohe ence
Tomog aphy
637Page www.ijhm .com 5 22011 No embe Issue 4IJHMR, Volume 0
Sample e al., in he A ican Descen and Glaucoma E alua ion S udy (ADAGES I) epo ed a smalle mean neu o- e inal im a ea
han ha ob ained in his s udy o 1.76mm² (+0.2) [24]. They e alua ed disc pa ame e s using OCT on samples o A ican descen
and compa ed hem o hose o Eu opean ances ies. They ound a mean im a ea o 1.53mm² among he heal hy subjec s. The im
a ea was also ound o be s a is ically signi ican ly hicke (1.58 mm²) among hose o A ican descen han ha o Eu opean descen
(1.38 mm²). The inding o his s udy also showed a hicke im a ea han ha epo ed by a s udy [25] among whi es (1.27 mm²)
and in A ican Ame icans (1.18 mm²). They used he Rodens ock disc analyse (RODA) o op ic ne e head examina ion, and his
migh ha e a ec ed he acqui ed images, so hei esul may no be en i ely compa able o ou indings. Thicke neu o- e inal im
a eas we e epo ed by many o he s udies [23,24,26]. The mean neu o e inal im a ea obse ed in his s udy was close o wha was
epo ed by Shaun [15] in India (1.77 mm²). Howe e , in his s udy, a wide ange o he im a ea was obse ed among he subjec s
(1.00 mm² o 3.03 mm²) agains 0.68 mm² o 0.83 mm² epo ed by he Indian esea ch. The sample size in his s udy (770) was
much la ge han ha o he esea ch (150) and migh ha e ec ui ed subjec s wi h a wide ange o im a ea.This s udy ob ained a
mean e ical cup-disc a io ( CDR) o 0.44 in all subjec s. This alue was highe han ha epo ed in a s udy by Tsai e al. among
whi es, Hispanics, and Asians (0.27, 0.33, and 0.29, espec i ely) [26]. The CDR hey ob ained among A ican Ame icans was s ill
smalle (0.41) han ha in his s udy. Ou inding o mean CDR was also highe han ha epo ed by Gi kin [24] who also used a
simila OCT echnique as ha o his s udy. In hei coho o 634 pa icipan s, hey made linea eg ession adjus men s o axial
leng h and e inal ne e ib e laye (RNFL). Unco ec ed, howe e , hey ob ained jus sligh ly highe mean alue (0.46) o CDR
han ha ound in his s udy. Mean CDR ob ained in his s udy is in ag eemen wi h wha Knigh and colleagues [17] ob ained
using a simila OCT ype and p o ocol on 271 pa icipan s o di e en e hnici ies. When co ec ed o he ace, he CDR obse ed
among A icans was sligh ly la ge (0.50) han ou inding. Al hough he Blue Moun ain Eye S udy [27] conduc ed among he whi e
popula ion employed subjec i e undus indi ec oph halmoscopy o op ic disc examina ion as agains a mo e objec i e
measu emen used in his s udy, hey obse ed simila (0.44) CDR indings. Simila ly, s udies [1,4,23,24] mos ly om India, all
epo ed la ge CDRs han wha was ob ained in his s udy. All hese s udies examined he op ic disc wi h a S a us OCT and did
simila ONH scan p o ocols like ou s udy. The di e ence may, he e o e, be due o a ia ion in e hnic in luence o smalle sample
sizes o hese s udies. Some s udies in A ica also epo ed highe CDR alues han hose obse ed in his s udy. Fo example, in
Egyp , Tha wa [2] epo ed a mean CDR alue o 0.62 among he popula ion. The s udy used he HRT cSLO machine in hei
esea ch and ob ained a highe mean CDR. They concluded ha hei indings migh be due o he e ec o e ac i e e o
magni ica ion, as many o hei subjec s we e obse ed o ha e axial myopia.
This s udy ound a s a is ically signi ican la ge male disc a ea (2.34 mm²) han ha o emale subjec s (2.29 mm²). Mean im a ea
was also ound o be la ge in males han in emales, and he di e ence was s a is ically signi ican . The e was also a conside able
di e ence in he cup-disc a io. The di e ence in ho monal in luence migh ha e esul ed in his di e ence as p oposed by many
s udies [1,7,28]. Howe e , he axial ocula leng h may cause image magni ica ion and hence, he signi ican di e ence. Bou ne e
al. epo ed simila signi ican gende di e ences in he Tanjong Paga s udy in Singapo e, whe e disc pa ame e s we e obse ed o
be signi ican ly highe in males han in he emales [29] In India [4] and he Uni ed S a es o Ame ica [27], simila la ge discs a ea
among males was epo ed. The Indian s udy, howe e , did no ind he di e ence o be o s a is ical signi icance.
In ag eemen wi h he gende di e ence indings o his s udy, a s udy [23] among he Indian popula ion obse ed ha disc a ea
among males was signi ican ly mo e ex ensi e han ha o emales in hei s udy. As emales in hei s udy had sho e axial leng h,
hey concluded ha he gende -based di e ence obse ed was likely due o axial magni ica ion. Ou s udy also con o ms o he
indings o G ozdeno ić [30], who also showed a simila gende ela ionship. They ound ha disc a ea and CDR we e signi ican ly
highe in males han in he emale subjec s. E en a e co ec ion o e ac i e e o and axial leng h, s a is ically signi ican gende
associa ion was appa en . The gende di e ences o he disc pa ame e s obse ed in his s udy we e di e en om hose o a s udy
among an Asian popula ion, as obse ed by Mansou [23], who did no show any signi ican gende di e ence wi h ONH
pa ame e s.
Neu o- e inal im hinning wi h inc easing age has been p oposed o e he yea s in he li e a u e [31]. The ageing p ocess may
p omo e ee adicals, inducing apop o ic loss o he e inal ganglion cell, which mani es s as im hinning [31]. This s udy obse ed
a s a is ically signi ican (p = 0.001) decline in neu o- e inal im a ea (RA) among he olde subjec s. A e adjus ing o sex, im
a ea was s ill s a is ically associa ed wi h age. Ve ical cup- o-disc a io ( CDR) was also ound o be signi ican ly la ge in he
olde subjec s. Reduc ion in he im a ea among he olde subjec s obse ed in his s udy was no demons a ed in he su ey by
Budenz and colleagues [32] who did no ind any signi ican RA decline in all he age g oups. Tha could be because hei subjec s’
ages we e clus e ed a ound 40 yea s, and he e o e, no signi ican di e ence was obse ed. Simila ly, he Vello e eye s udy in India
[4] did no show any c i ical age ela ionship wi h ONH pa ame e s a e co ec ion o gende . The smalle sample size (70 subjec s)
han his s udy migh ha e esul ed in ha ing no signi ican di e ence. The simila age- ela ed di e ence obse ed in his s udy was
demons a ed by a s udy in Kano, Nige ia [3], which ound ha pe ipapilla y im a ea declined s eadily wi h ad ancing age.
Simila ly, ou inding was also in suppo o wha was obse ed in Came oon, in a s udy among u al sou he n Came oonians [33]
Mo phome ic S udy o he Op ic Ne e Head Among No he n Nige ian Adul s, Using Op ical Cohe ence
Tomog aphy
638Page www.ijhm .com 5 22011 No embe Issue 4IJHMR, Volume 0
Using undus pho og aphy, hey ound an a e age CDR o 0.15 in he younges and 0.45 in he oldes subjec s. The posi i e
co ela ion hey obse ed was no e y a om he inding o his s udy e en hough hey used a di e en examina ion p ocedu e.
S eng hs and Limi a ions
Only a ew s udies we e conduc ed abou ONH dimensions among Nige ian, and no such was done in he no he n Nige ia whe e
glaucoma is p e alen . The u ilisa ion o mo e han 700 s udy sample could be a s eng h o some ex en . Ob aining a s ong s a is ical
ool ( eg ession analysis) o calcula e empi ically he ONH dimension among adul could also sugges a ai ly s ong clinical
conclusion.
We d ew ou samples only om Hausa e hnic popula ion while he e a e o e 250 e hnic g oups in Nige ia. The e o e, in o de o
ob ain a mo e gene alised da a wi h a be e clinical conclusion, s udies need o be ca ied ou among o he e hnic g oups, o
de e mine i he e a e a ia ions in he indings. Fu he s udies should also include mo e ocula and sys emic de e minan s o he
ONH.
CONCLUSION
No mal e e ence alue o he Op ic Ne e Head mo phome ic pa ame e s (DA, CA, RA and CDR) in no mal no he n Nige ian
adul s was p esen ed in his s udy. We ound ha op ic disc pa ame e s a e sligh ly la ge in he le , bu no s a is ically signi ican .
All he pa ame e s we e ound o be signi ican ly la ge in males, excep o he CA. The e is signi ican age a ia ion, as he DA
and he CDR we e la ge in he olde pa ien , and he neu o- e inal im (RA) was hinnes in hem. The eg ession equa ions
ob ained in he s udy may be use ul in es ima ing di e en ONH dimensions om pa ien ’s age. This inding would se e as a
e e ence alue among adul s and could be used as a sc eening ool in diagnosis and managemen o glaucoma and o he op ic
neu opa hy.
LIST OF ABBREVIATIONS
ONH – Op ic Ne e head
OCT - Op ical Cohe ence Tomog aphy
DA – Disc a ea
RA – Rim a ea
CA – Cup a ea
CDR – Ve ical cup o disc a io
FUNDING
This p ojec is Sel - unded
DECLARATION
The au ho (s) decla e ha hey ha e no compe ing in e es .
ACKNOWLEDGEMENT:
We wan o acknowledge he suppo gi en by managemen and s a o he oph halmic depa men o Aminu Kano eaching
Hospi al, Baye o Uni e si y Kano, Nige ia. Also, he managemen o Makka Specialis Eye Hospi al, Kano Nige ia o g an ing
access o he OCT machine o pilo aining and all he olun ee s ha consen ed o be examined as s udy subjec s, and hei
ela i es o hei pa ience
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