• Users Online: 202
  • Print this page
  • Email this page

 Table of Contents  
Year : 2021  |  Volume : 59  |  Issue : 2  |  Page : 190-192

Hydrops as the presenting sign and “inverted bell sign” as a diagnostic sign of atypical pellucid marginal degeneration

Department of Cornea, Aravind Eye Hospital, Tirunelveli, Tamil Nadu, India

Date of Submission17-Jan-2021
Date of Acceptance01-Apr-2021
Date of Web Publication24-Jun-2021

Correspondence Address:
Dr. Venugopal Anitha
Aravind Eye Hospital, S.N High Road, Tirunelveli Junction, Tirunelveli - 627 001, Tamil Nadu
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/tjosr.tjosr_5_21

Get Permissions


To report a case of, atypical pellucid marginal degeneration (PMD) with hydrops and to describe the inverted bell sign as the diagnostic feature in topography. A 40-year-old male presented to us with acute pain, redness, and loss of vision. On examination, hydrops was noted in the superior cornea in the right eye and advanced PMD in the left eye. The typical topographic signs of PMD have been described. The conservative management of hydrops in our case resulted in improvement in visual acuity. Early diagnosis and treatment of this condition with regular follow-up are essential for a good visual prognosis in these patients.

Keywords: Atypical pellucid marginal degeneration, bell sign, hydrops, inverted bell sign

How to cite this article:
Anitha V, Ravindran M, Ghorpade A. Hydrops as the presenting sign and “inverted bell sign” as a diagnostic sign of atypical pellucid marginal degeneration. TNOA J Ophthalmic Sci Res 2021;59:190-2

How to cite this URL:
Anitha V, Ravindran M, Ghorpade A. Hydrops as the presenting sign and “inverted bell sign” as a diagnostic sign of atypical pellucid marginal degeneration. TNOA J Ophthalmic Sci Res [serial online] 2021 [cited 2021 Aug 5];59:190-2. Available from: https://www.tnoajosr.com/text.asp?2021/59/2/190/319257

  Introduction Top

Pellucid marginal degeneration (PMD) is an idiopathic, ectatic disorder of the peripheral cornea. It mostly involves the inferior quadrant in a crescentic fashion;[1] however, literature evidence has shown involvement in the superior,[2],[3] temporal,[4] and nasal[5] quadrant of the cornea. Patients with PMD typically complain of gradual, progressive loss of vision or long-standing poor visual acuity, due to irregular against the rule astigmatism with onset in the third to fourth decade of life.[4] Rarely, patients present with acute hydrops and/or spontaneous corneal perforation. Acute hydrops occurs more commonly in keratoconus (KC) than PMD.[6] We present a case of a 40-year-old male with acute hydrops following PMD in an atypical location as the initial presenting sign.

  Case Report Top

A 40-year-old male patient presented to us with a sudden onset of pain, redness, and defective vision in the right eye for the past 3 days. He had no history of eye rubbing or contact lens wear in the past. His medical history was unremarkable. The best-corrected vision in the right eye was 20/200; the left eye was 20/25 with-6Dcylinder at 75° He has been using glasses for the past 2 years. On slit-lamp examination, right eye revealed dense superior and central corneal edema with superior crescentic thinning from 10'0 clock–2'0 clock, 1 mm anterior to the superior limbus, and semicircular defect in the Descemet's membrane was noted just above the nasal pupillary margin, the size was not measurable due to severe edema [Figure 1]a. The left eye appeared clinically normal. However, the keratometry was 56.3D at 166°, 42.4D at 76°, anterior sagittal map in corneal topography (ORBSCAN III) of the left eye revealed superior peripheral steepening, the classic “crab-claw” appearance and the typical “Inverted Bell sign” in the pachymetric map suggestive of superior atypical PMD in the left eye [Figure 2]. Hence, the diagnosis of acute hydrops in the right eye was made. He was started on hypertonic saline drops 5% four times a day, homatropine 2% eye drops twice a day, and Gatifloxacin 0.3% eye drops four times a day in the right eye. The corneal edema resolved over 4 weeks with scarring and improvement in the visual acuity to 20/40 unaided. The site of DM break was seen clearly after edema resolved, which was noted below the area of thinning [Figure 1]b. In the left eye, he was advised cross-linking with riboflavin and counseled for regular follow-up with sibling screening. During his last visit, the Pentacam revealed the advanced stage of “Inverted Bell sign” in the pachymetric map [Figure 3].
Figure 1: (a) Shows the right eye with acute hydrops on presentation. (b) Shows the right eye with resolved hydrops after 4 weeks of conservative management

Click here to view
Figure 2: Shows the left eye topographic picture with the crab claw pattern in the anterior elevation map and inverted bell sign in the pachymetric map

Click here to view
Figure 3: Shows pentacam image of advanced inverted bell sign in the pachymetric map

Click here to view

  Discussion Top

Atypical location of PMD has previously been reported in the literature, but we have noted hydrops as the presenting sign in our patient and described a diagnostic sign “Inverted Bell Sign” in the topography. Tagalia and Sugar have reported two cases of superior PMD.[3] Rao et al. had noted nasal PMD in his series of five patients with atypical PMD.[5] Puy et al. reported temporal PMD with the with-rule–astigmatism.[4] Our patient was not aware of the disease condition and was wearing glasses for the past 2 years. He presented to us with corneal edema in the right eye as the first clinical sign, left eye revealed atypical PMD in the superior location in the topographic maps. With the diagnosis of left eye topography, the right eye condition was identified as acute hydrops. Acute hydrops is the development of marked corneal edema of the stroma and the epithelium following a break in the Descemet's membrane. It is well known to occur in KC but rare in PMD. The incidence of acute hydrops in PMD and KC is 2.5%–6%.[7] The predisposing factors are allergies, eye rubbing, and traumatic contact lens (CL) insertions. The reason for hydrops might be due to patient's insentient act of lid pressure, causing microtrauma and thereby the pathogenesis of hydrops. The choice of conservative management was made due to two reasons, since the surgical intervention either with air/gas or compression sutures may lead to perforation because of extreme thinning noted superiorly; the compression sutures for the DM break would involve the visual axis and can distort the corneal contour. The resolution of hydrops causes corneal scarring and flattening, thereby improving the visual acuity as reported previously by Tuft et al.[8] Another unique feature was classical topographical patterns in the left eye which led to the diagnosis in our patient. The “bell sign” is the diagnostic feature of typical PMD, which differentiates it from other PMD such as KC maps. The “Bell sign” in the pachymetric map is described as vertical elliptic inferior thinning noted in typical case of PMD.[9] The superior crab-claw pattern in the anterior sagittal map and the “Inverted Bell sign” is the hallmark patterns of superior PMD recognized in the left eye of our patient. The word “Inverted Bell sign” was coined to denote the reversal of bell sign in the pachymetric map of the classic inferior PMD [Figure 3]. The vision-threatening complications do occur in PMD. Serious complications such as perforation and secondary infective keratitis have been reported in the literature. The management of PMD is difficult compared to KC due to the involvement of the peripheral cornea. Nowadays, cases of superior PMD are being increasingly reported, early diagnosis; promotion of awareness about this condition in general ophthalmologists is imperative. The regular follow-up will lead to a good prognosis in these patients.

To conclude, hydrops in superior PMD can occur due to trivial lid pressures. Initially, conservative management of hydrops should be ventured before surgical methods. The new term coined as “Inverted Bell sign” can be considered as the diagnostic sign in superior PMD in the future. Topography is the gold standard for the diagnosis of corneal ectatic disorders and superior PMD also to be regarded in the differential diagnosis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Dundar H, Kara N, Kaya V, Bozkurt E, Yazici AT, Hekimhan PK. Unilateral superior pellucid marginal degeneration in a case with ichthyosis. Cont Lens Anterior Eye 2011;34:45-8.  Back to cited text no. 1
Sridhar MS, Mahesh S, Bansal AK, Rao GN. Superior pellucid marginal corneal degeneration. Eye (Lond) 2004;18:393-9.  Back to cited text no. 2
Taglia DP, Sugar J. Superior pellucid marginal corneal degeneration with hydrops. Arch Ophthalmol 1997;115:274-5.  Back to cited text no. 3
Puy P, Stoica BT, Alejandre N, Toledano N. Temporal pellucid marginal degeneration displaying high “with-the-rule” astigmatism. Can J Ophthalmol 2013;48:e142-4.  Back to cited text no. 4
Rao SK, Fogla R, Padmanabhan P, Sitalakshmi G. Corneal topography in atypical pellucid marginal degeneration. Cornea 1999;18:265-72.  Back to cited text no. 5
Jinabhai A, Radhakrishnan H, O'Donnell C. Pellucid corneal marginal degeneration: A review. Cont Lens Anterior Eye 2011;34:56-63.  Back to cited text no. 6
Bhandari V, Ganesh S. Corneal hydrops in pellucid marginal degeneration: A case series. Case Rep Ophthalmol 2015;6:191-9.  Back to cited text no. 7
Tuft SJ, Gregory WM, Buckley RJ. Acute corneal hydrops in keratoconus. Ophthalmology 1994;101:1738-44.  Back to cited text no. 8
Sinjab MM, Youssef LN. Pellucid-like keratoconus. F1000Res 2012;1:48.  Back to cited text no. 9


  [Figure 1], [Figure 2], [Figure 3]


Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

  In this article
Case Report
Article Figures

 Article Access Statistics
    PDF Downloaded18    
    Comments [Add]    

Recommend this journal