An Experimental Study of Astigmatism
Optical Correction on Visual Acuity Changes when being Corrected with Spherocylindrical and Spherical Equivalent Spectacle Lenses
Master’s Degree in Optometry and Vision Therapy, Zomba Central Hospital, Malawi
Submission: January 12, 2019; Published: February 05, 2019
*Corresponding author: Innocent Thawe, School of Advanced Education, Research and Accreditation, Master’s Degree in Optometry and Vision Therapy, Zomba Central Hospital, Zomba, Malawi
How to cite this article: Innocent T. An Experimental Study of Astigmatism Optical Correction on Visual Acuity Changes when being Corrected with Spherocylindrical and Spherical Equivalent Spectacle Lenses. JOJ Ophthal. 2019; 7(3): 555713. DOI: 10.19080/JOJO.2019.07.555713
Marfan’s disease (MDM) is a hereditary connective tissue disorder transmitted in the dominant autosomal mode with variable penetrance and expressiveness. It is responsible for a clinical polymorphism, which can be life threatening (heart, aorta) and functional (eye, skeleton, ...). The lens ectopia is one of the most common eye manifestations, and represents a major criterion of diagnosis. The aim of our study was to study the ocular manifestations and to evaluate the management and evolution of this pathology through seven (07) observations made at the Ophthalmology Clinic of Aristide Le Dantec Hospital in Dakar, between January 2009 and December 2015.
This was a 40-year-old female teacher who was screened and followed at age 17. She had a brother and a sister in the morphotype of Marfan, who died in May and December 2014 respectively of an undocumented cardiac pathology. She had consulted for a progressive BAV with both eyes evolving since the age of seven. The general examination showed a slender morphotype (size 1.90m), dolichostomelia, arachnodactyly and ligamentous hyperlaxity (Figure 1-5). AV was 1/10th at OD and CLD at 50cm at OG. In the slit lamp (LAF) there was bilateral ectopia (Figure 7) with supero-nasal displacement, cortical opacity and bilateral iridodonesis. The ocular tone was 14mmHg at ODG and the fundus revealed diffuse choroidosis. The cardiovascular examination was normal. Automatic refraction with cyclopentolate showed strong myopia with astigmatism at -18.5 (120° -12.25) at OD and -19 (60-12.5) at OG. Mean keratometry was 8.2mm at OD and 8.5mm at OG. The electrocardiographic tracing was normal and echocardiography in the TM and 2D mode revealed an undilated ascending aorta 30 mm in diameter with minimal aortic insufficiency. The diagnosis of MDM was made before ocular, morpho-skeletal, and cardiological abnormalities that met the diagnostic criteria of Ghent 2010. The indication of lens extraction and placement of an implant attached to the sclera had been proposed, but the patient had refused surgery. An optic correction was made OD : -7 (120° - 4); OG: -7 (60° - 4) and the bilateral AV was ≤ 3/10th.
This was a 34-year-old patient, brother of patient no 1. He had come in consultation on our request for MDM screening.Examination showed a slender morphotype (size 2.02 m), dolichostomelia, arachnodactyly, dolichocephaly, ligamentous hyperlaxity and valgus flat feet (Figure 1-6). AV was 7/10th at OD, and 5/10th at OG. At the LAF, there was a bilateral ectopic lens (Figure 7) with a super-nasal direction, and a bilateral iridodonesis. The ocular tone was at 16mmHg at ODG and normal fundus. The cardiovascular examination was normal. Automatic refraction with cyclopentolate showed moderate myopia associated with astigmatism with -1.00 (177° -2.25) at OD and -1.50 (30° -3.50) at OG. Mean keratometry was 7.5mm at OD and 7.8mm at OG. The electrocardiographic tracing revealed atrioventricular block with left ventricular hypertrophy. TM and 2D echocardiography showed moderate dilatation of the aorta with minimal aortic insufficiency. Faced with family history, ocular, morpho-skeletal, and cardiological abnormalities that met the international criteria of Ghent 2010, the diagnosis of MDM was retained. The treatment consisted of a total optical correction with AV at 9 / 10th to OD, and 7/10th at OG, a bêta-blocker prescription in per os and periodic monitoring.
This was a 14-year-old woman with a history of multiple lens prescription ametropia who had been referred for a progressive ODG BAV that had been on the move since the age of eight. The examination revealed an elongated morphotype (size 1.74m), dolichostomelia, arachnodactyly and ligamentous hyperlaxity
Keywords: Marfan’s disease; Hereditary connective tissue; Clinical polymorphism; Heart; Aorta; Eye; Skeleton; Lens ectopia; Eye manifestations; Diagnosis; Pathology; Ophthalmology clinic (Figure 1-5). The AV was at CLD at 1m at OD and at CLD at 2m
at OG. Ophthalmologic examination revealed an esotropia of
OG, a crystalline ectopia (Figure 7) bilateral with supernonasal
orientation. The ocular tone was at 12mmHg at OD and 14mmHg
at OG. The fundus was normal. The cardiovascular examination
was normal. Automatic refraction with cyclopentolate showed
strong myopia associated with astigmatism in both eyes: -12
(130° -10) at OD and -14 (63°-11.25) at OG. Electrocardiographic
tracing was normal, and TM and 2D echocardiography showed
moderate dilatation of the aorta with minimal aortic insufficiency.
MDM was found in association with ocular, morpho-skeletal
and cardiological disorders that were consistent with the 2010
Ghent diagnostic criteria. The patient had scleral crystalline
lens removal with optic correction of aphakia by glasses (AV
at 3 / 10th ODG), oral betablocker prescription and periodic
This was a 21-year-old patient who had been seen for a
progressive implantable BAV since the age of 8, and bilateral
eye pain. The examination showed a slender morphotype
(size 1.93m), dolichostomelia, arachnodactyly, ligamentous
hyperlaxity and valgus flat feet (Figure 1-6).
Ophthalmologic examination showed CLD at 50cm ODG,
stage IV keratoconus (Figure 8) and bilateral central corneal
opacity. The ocular tone was 28mmHg at ODG. The fundus
was normal. The cardiovascular examination was normal.
Automatic refraction was impregnable at ODG. Keratometry and
electrocardiogram could not be performed. Echocardiography
in TM and 2D mode noted moderate dilatation of the aortic
arch (37mm). The diagnosis of MDM was based on ocular,
morpho-skeletal and cardiological abnormalities that met the diagnostic criteria of Ghent 2010. A medical treatment based on
hypotonizing eye drops was prescribed. The patient was then
lost to sight for three years. After this delay, the ophthalmological
examination showed an AV at CLD less than 50cm at OD and a
light perception at OG. The LAF examination was unchanged
and associated with a bilateral debutative cortical cataract. The
papilla was viewable without interposition of magnifying glass.
The ocular tone was 12mmHg at ODG.
This was a 28-year-old female patient with a history of
ametropia who had been prescribed corrective lenses several
times, who had been referred for an ODG progressive implant
BAV that had been in the process since the age of 6, persistent
despite the glasses. Examination showed a slender morphotype
(size 1.85m), dolichostomelia, arachnodactyly, dolichocephaly,
ligamentous hyperlaxity and dorsal kyphosis (Figure 1-5).
Ophthalmologic examination revealed CLD AV at 1m ODG. LAF
examination revealed a superior-temporal erythropic ectopy at
ODG (Figure 7), cortical crystalline opacity, bilateral iridodonesis, and vitreous liquefaction. The ocular tone was at 14mmHg. The
fundus was normal to ODG. The cardiovascular examination
was normal. Automatic refraction with cyclopentolate showed
strong myopia and astigmatism at -18.25 (140° -12) at OD, and
-18.50 (75°-12.50) at OG. Mean keratometry was 8.3mm at OD
and 8.55 mm at OG. Ocular ultrasonography in B mode showed
posterior detachment of vitreous to OG. Electrocardiographic
tracing demonstrated left ventricular hypertrophy and TM
and 2D echocardiography showed a linear image in the lumen
of the proximal aorta. The diagnosis of MDM was based on
ocular, morpho-skeletal, and cardiological abnormalities
that corresponded to the 2010 Ghent diagnostic criteria. A
lens extraction without implant placement was proposed
and performed at OG, but was refused to OD by the patient.
The cardiological treatment consisted of the prescription of
betablocker and periodic monitoring. The patient was regularly
seen post-operatively. In the 5th month, the AV was unchanged
at OD while at OG a BAV was noted with a reduced vision at PL
+. FO at OG showed a retinal detachment with a tear. A strapping
had been indicated and carried out without success.
This was a 17-year-old patient who had been referred for an
ODG progressive implant BAV that had been evolving since she
was 5 years old. Examination revealed a slender morphotype
(size 1.96m), dolichostomelia, arachnodactyly, ligamentous
hyperlaxity, and dorsal kyphosis (Figure 1-5). Ophthalmologic examination showed 1/20 AV at ODG. LAF examination revealed
bilateral posterior dislocation of the ectopic lens associated
with ODG microspherophakia. The ocular tone was 6mmHg at
ODG. The fundus showed a nasal retinal detachment lower than
ODG. The cardiovascular examination was normal. Automatic
refraction with cyclopentolate showed strong myopia associated
with astigmatism with -15 (125°-10) at OD and -14 (70°-11.25)
at OG. Mean keratometry was 7.8mm at OD and 7.9mm at OG.
TM and 2D echocardiography revealed moderate dilatation
of the aorta with minimal aortic insufficiency. The diagnosis
of MDM was based on the combination of ocular, morphoskeletal,
and cardiological disorders that were consistent with
the 2010 Ghent diagnostic criteria. The patient had benefited
from a simple extracapsular lens extraction (EEC) with ODG.
Betablocker-based therapy and periodic monitoring. The patient
had a post-operative AV PL + with intravitreous hemorrhage at
OD and CLD at 5m to 0G.
This was a 14-year-old patient with a family history of MDM
who had been consulting for a 8-year progressive ODG BAV.
The examination revealed a slender morphotype (size 1.75m),
the fingers and toes were tapered. There was dolichostomelia,
arachnodactyly, dolichocephaly and ligamentous hyperlaxity
(Figure 1-5). Ophthalmologic examination revealed an AV at
2/10th at OG, and PL + at OD. The LAF examination noted a
bilateral super-nasal crystalline ectopia (Figure 7). The ocular
tone was at 14mmHg at ODG. The fundus showed bilateral
myopic colon and temporal peripapillary chorioretinal
degeneration. The cardiovascular examination was normal.
Automatic refraction under cyclopentolate was not feasible.
Mean keratometry was 8.2mm at OD and 8.3mm at OG.
Electrocardiogram and echocardiography were requested but
not done for lack of means. The diagnosis of MDM was made
before eye, morpho-skeletal and cardiological abnormalities
that met the diagnostic criteria of Ghent 2010. The patient was
lost sight of after the first consultation.
Marfan’s disease is rare, its frequency is estimated in the
literature at 3-5 / 10000 , in our context its prevalence was
3/10000. Sun et al. reported a prevalence of 17.2 per 100,000
consultants in China . The average age of diagnosis of the
disease in our patients was 20.7 years, with extremes of 14
and 34 years. In the United States, Heur et al.  reported an
average age of 22.3 years . In France, Sultan had reported an
average age of 23.9 years . The diagnostic delay observed can
be explained by the fact that the diagnosis is sometimes difficult,
particularly in pediatrics, because of the great variability of
expression of the disease, ranging from a very severe form
(neonatal Marfan) to a form with a clinical expression is not
very intense and because of the evolution of signs with age .
Neonatal MDM is considered the most severe form of type 1
fibrillinopathy. In an international series of 62 patients , over
80% of children died before the age of one. In the literature,
Marfan’s disease affects both sexes . The familial character
was found in fours patients. Maumenee, noted a family history
in 111 patients (69.3%), against 46 without a family history of
Marfan disease . Almost 25% of sporadic cases are due to new
mutations in the MFS gene and the notion of family inheritance
is not always a risk factor . Low vision is the first reason for
consultation, it is found in six (06) of our patients. Visual acuity
was less than or equal to 1/10th in 11 out of 14 eyes. This is
due to delayed consultation of patients who mostly reside in a
rural area with low socio-economic status and lack of campaigns
screening for this type of pathology. The crystalline ectopia is of
great semiological value. It is a major criterion in the diagnosis of
MDM. In the literature, it represents 60 to 80% [9,10]. Bilateral
involvement is found in all our patients. In Norway, a study by
Drolsum et al.  about 87 cases of MDM reported 62.1% of
ectopic lens, with bilateral and symmetrical involvement .
The superior direction of ectopia is reported in the literature
[9,10,12]. Iridodonesis is a sign often associated with ectopia
[10,11]. Posterior dislocation of the ectopic lens is a complication
of Marfan’s disease. It can be followed by retinal detachment .
Chefchaouni in Morocco reported posterior dislocation in 5 out
of 38 eyes with lens ectopia .
Microspherophakia is described in 15% . Cataract was
present in 4 out of 14 eyes. In the Chefchaouni series, it has been
observed in 6 out of 40 eyes. In Norway, the study by Drolsum
et al. showed 20% cataract . While the rate was 12% in the
Konradsen et al. . Myopia is the second most common ocular
manifestation in Marfan’s disease with a significant incidence of
strong myopia (greater than -6 diopters). In Sweden, Konradsen
et al. reported 87% myopia, of which 39% had moderate myopia
. Maumenee revealed 16.3% of strong myopia . Five
patients had strong myopia, one patient had moderate myopia
and. This disparity in the results can be due on the one hand
to the weakness of our sample, on the other hand to the delay
of consultation. This abnormality of refraction also exposes to
classic retinal complications, sometimes serious, of the strong
myopia. Among these complications, we can note retinal
detachment and chorioretinal atrophy noted respectively in
two (02) of our patients. The detachment of the retina is the
main ocular complication of Marfan’s disease. Its frequency is
estimated at 5 to 11%. The risk of DR is increased in case of
ectopic lens or after lens extraction (8 to 38%) . It usually
occurs around the twenties, and mainly affects men . The
incidence of bilateral retinal detachment is also high and can
reach 69% according to some studies [17,18]. Various factors
are implicated in the etiopathogenesis of this complication,
notably crystalline ectopia which exerts a continuous traction on
the ora serrata, the vitreous liquefaction causing retinal traction
and the coexistence of myopia and therefore of degenerative
lesions of the retinal periphery. Only one case of keratoconus
was recorded at an advanced stage. This manifestation is rarely
linked to MDM . Crystal ectopia is a relatively easy anomaly
to identify when it is known, but management is a real challenge
for ophthalmologists. Optical correction is one of the therapeutic
means adopted when ectopia is simple, uncomplicated and
without significant refractive errors. Most authors resort to
surgery if any of these elements exist [9,10]
a) A bad AV not paired with glasses or contact lenses;
b) A myopia greater than 7 diopters and / or a higher astigmatism 4 diopters;
c) A cataract;
d) A glaucoma;
e) A crystalline dislocation.
The surgical procedure under the operating microscope and
with maximal mydriasis consisted of a simple EEC for 4 eyes of
3 patients, with correction of aphakia by glasses for a patient. A surgical cure of retinal detachment was performed in one patient.
In the Chefchaouni series, an EEC by phacophagia with anterior
vitrectomy by pars plana was performed for 14 eyes. One patient
had intraocular lens implantation. Three eyes underwent a
retinal detachment and 9 eyes with degenerative lesions of the
retinal periphery benefited from Argon laser photocoagulation.
A study done in London by Hubbard et al. , about 30 cases of
Marfan’s disease, reported an EEC by phacophagia with anterior
vitrectomy by pars plana in 40 eyes. Thirty-seven eyes had a
simple EEC and had been corrected by contact lenses. Three
eyes benefited from implantation in the posterior chamber.
Seven eyes had a retinal detachment cure. The results and the
postoperative complications that the different studies show
are variable. Poncophagia associated with anterior vitrectomy
by pars plana remains the most used. It would decrease the
risk of postoperative retinal detachment by reducing traction
forces on the vitreous base [13,19]. The functional results after
lens extraction were 3 / 10th improvement in AV for 2 eyes of a
patient after correction of aphakia with glasses of glasses and
worsening of BAV at PL + in 2 patients, due to postoperative
retinal detachment and intravitreous hemorrhage. A study
conducted in India by Sinha et al.  about 10 eyes of 5 patients
who had lens-free crystalline extraction, corrected for aphakia
by glasses, showed a mean postoperative AV of 0.46 ± 0.15
(preoperatively, it was 0,16 ± 0.07) . The functional results
of Chefchaouni, after phacophagia, without implant placement,
and anterior vitrectomy reported an AV greater than or equal to
2/10th in 85% of cases. In addition, for 3 eyes having benefited
from a retinal detachment cure, a retinal reapplication could be
obtained in 2 cases.
Marfan’s disease is an inherited connective tissue disorder,
transmitted in an autosomal dominant fashion with variable
penetrance and expressiveness. It is often due to a mutation in
the gene encoding type 1 fibrillin, located on chromosome 15
(15q21). The lens ectopia is one of the most frequent ocular
manifestations, and represents a major diagnostic criterion. The
management of ocular disorders remains difficult.